@article{lee_kim_son_shim_whangbo_2020, title={Ternary selenides A(2)Sb(4)Se(8) (A = K, Rb and Cs) as an n-type thermoelectric material with high power factor and low lattice thermal conductivity: importance of the conformationally flexible Sb-Se-Se-Sb bridges}, volume={10}, ISSN={["2046-2069"]}, DOI={10.1039/d0ra01751e}, abstractNote={The ternary selenides A2Sb4Se8 (A = K, Rb, Cs) are predicted to be a high-performance n-type thermoelectric material, and the conformationally-flexible Sb–Se(2)–Se(2)–Sb bridges are crucial in determining the thermoelectric properties of A2Sb4Se8.}, number={24}, journal={RSC ADVANCES}, author={Lee, Changhoon and Kim, Sujee and Son, Won-Joon and Shim, Ji-Hoon and Whangbo, Myung-Hwan}, year={2020}, month={Apr}, pages={14415–14421} }
 @article{lee_shim_whangbo_2018, title={Cause for the Orbital Ordering of Cs2AgF4 and Its Effect on Thermoelectric Properties}, volume={57}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.8b01037}, abstractNote={The cause for the orbital-ordered structure of orthorhombic Cs2AgF4 and its effect on thermoelectric properties were probed by density functional theory calculations. The orbital-ordered structure of orthorhombic Cs2AgF4 has been regarded as caused by a cooperative Jahn-Teller (JT) distortion of the AgF6 octahedra of tetragonal Cs2AgF4. However, each AgF6 octahedron of tetragonal Cs2AgF4 is axially compressed and hence has no JT instability. The orbital-ordering transition of Cs2AgF4 is best described as a metal-to-insulator transition driven by a bandgap opening at the Fermi level. The orbital-ordering opens a bandgap at the Fermi level and generates peaks in the density of states at the conduction band minimum (CBM) and valence band maximum (VBM). Consequently, orthorhombic Cs2AgF4 has strongly enhanced Seebeck coefficients as compared to tetragonal Cs2AgF4.}, number={19}, journal={INORGANIC CHEMISTRY}, author={Lee, Changhoon and Shim, Ji-Hoon and Whangbo, Myung-Hwan}, year={2018}, month={Oct}, pages={11895–11900} }
 @article{lee_kim_tak_cho_shim_lim_whangbo_2018, title={Comparison of the electronic and thermoelectric properties of three layered phases Bi2Te3, PbBi2Te4 and PbBi4Te7: LEGO thermoelectrics}, volume={8}, ISSN={["2158-3226"]}, DOI={10.1063/1.5047823}, abstractNote={The electronic and thermoelectric properties of Bi2Te3, PbBi2Te4 and PbBi4Te7 were examined on the basis of density functional theory (DFT) calculations and thermoelectric transport property measurements. The layered phase PbBi4Te7 is composed of the slabs forming the layered phases Bi2Te3 and PbBi2Te4. The electronic structure of PbBi4Te7 around the valence band maximum and conduction band minimum exhibits those of Bi2Te3 and PbBi2Te4. The band gap of PbBi4Te7 lies in between those of Bi2Te3 and PbBi2Te4, and the density of states of PbBi4Te7 is well approximated by the sum of those of Bi2Te3 and PbBi2Te4. In terms of the carrier concentration, the carrier mobility, the carrier lifetime, the electrical conductivity normalized to the carrier lifetime, and the effective mass, the layered phases Bi2Te3, PbBi4Te7 and PbBi2Te4 form a group of thermoelectrics, which have the structures composed of several different slabs and whose thermoelectric properties are approximated by the average of those of the constituent slabs. We propose to use the term “LEGO thermoelectrics” to describe such a family of thermoelectric materials that operate in a desired temperature range and possess predictable thermoelectric properties.}, number={11}, journal={AIP ADVANCES}, author={Lee, Changhoon and Kim, Jae Nyeong and Tak, Jang-Yeul and Cho, Hyung Koun and Shim, Ji Hoon and Lim, Young Soo and Whangbo, Myung-Hwan}, year={2018}, month={Nov} }
 @article{lee_hong_son_kan_shim_whangbo_2016, title={Magnetic structure of (C5H12N)CuBr3: origin of the uniform Heisenberg chain behavior and the magnetic anisotropy of the Cu2+ (S=1/2) ions}, volume={6}, ISSN={["2046-2069"]}, DOI={10.1039/c5ra26341g}, abstractNote={The AFM chain behavior observed for (pipH)CuBr3is not caused by the CuBr3chains, but by the interchain exchanges leading to two-leg spin ladders. The Cu2+ions have easy-axis anisotropy, and this arises largely from the SOC of the Br−ligands.}, number={27}, journal={RSC ADVANCES}, author={Lee, Changhoon and Hong, Jisook and Son, Won-joon and Kan, Erjun and Shim, Ji Hoon and Whangbo, Myung-Hwan}, year={2016}, pages={22722–22727} }
 @article{kenneth r. o'neal_holinsworth_chen_peterson_carreiro_lee_manson_whangbo_li_liu_et al._2016, title={Spin-Lattice Coupling in [Ni(HF2)(pyrazine)(2)]SbF6 Involving the HF2- Superexchange Pathway}, volume={55}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.6b01679}, abstractNote={Magnetoelastic coupling in the quantum magnet [Ni(HF2)(pyrazine)2]SbF6 has been investigated via vibrational spectroscopy using temperature, magnetic field, and pressure as tuning parameters. While pyrazine is known to be a malleable magnetic superexchange ligand, we find that HF2- is surprisingly sensitive to external stimuli and is actively involved in both the magnetic quantum phase transition and the series of pressure-induced structural distortions. The amplified spin-lattice interactions involving the bifluoride ligand can be understood in terms of the relative importance of the intra- and interplanar magnetic energy scales.}, number={23}, journal={INORGANIC CHEMISTRY}, author={Kenneth R. O'Neal and Holinsworth, Brian S. and Chen, Zhiguo and Peterson, Peter K. and Carreiro, Kimberly E. and Lee, Changhoon and Manson, Jamie L. and Whangbo, Myung-Hwan and Li, Zhigiang and Liu, Zhenxian and et al.}, year={2016}, month={Dec}, pages={12172–12178} }
 @article{lee_hong_stroppa_whangbo_shim_2015, title={Organic-inorganic hybrid perovskites ABI(3) (A = CH3NH3, NH2CHNH2; B = Sn, Pb) as potential thermoelectric materials: a density functional evaluationt}, volume={5}, ISSN={["2046-2069"]}, DOI={10.1039/c5ra12536g}, abstractNote={Our calculations show that, when doped by electrons, the organic–inorganic perovskite iodides ABI3(A = CH3NH3, NH2CHNH2; B = Sn, Pb) can be a good thermoelectric material with thermoelectric efficiency comparable to that of hole-doped Bi2Te3.}, number={96}, journal={RSC ADVANCES}, author={Lee, Changhoon and Hong, Jisook and Stroppa, Alessandro and Whangbo, Myung-Hwan and Shim, Ji Hoon}, year={2015}, pages={78701–78707} }
 @article{lee_kang_hong_shim_whangbo_2014, title={Analysis of the Difference between the Pyroxenes LiFeSi2O6 and LiFeGe2O6 in Their Spin Order, Spin Orientation, and Ferrotoroidal Order}, volume={26}, ISSN={["1520-5002"]}, DOI={10.1021/cm5001413}, abstractNote={The pyroxenes LiFeSi2O6 and LiFeGe2O6 are isostructural and isoelectronic, but they differ in their spin order, spin orientation and ferrotoroidal order. The reasons for these differences were probed by density functional theory electronic structure calculations and magnetic dipole–dipole (MDD) interaction energy calculations. The ferromagnetic Fe-zigzag chains of LiFeSi2O6 arise from the antiferromagnetic interchain spin exchanges and the antiferromagnetic Fe-zigzag chains of LiFeGe2O6 from the antiferromagnetic intrachain spin exchange. The preferred spin orientations of LiFeGe2O6 and LiFeSi2O6 are not caused by spin–orbit coupling but by MDD interactions. LiFeSi2O6 undergoes a ferrotoroidal order because it has spin exchange rings made up of an even number of antiferromagnetic spin exchanges paths with comparable strengths. A ferrotoroidal order is not expected for LiFeGe2O6 because it has no such spin exchange rings.}, number={4}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Changhoon and Kang, Jinhee and Hong, Jisook and Shim, Ji Hoon and Whangbo, Myung-Hwan}, year={2014}, month={Feb}, pages={1745–1750} }
 @article{lee_lee_lee_whangbo_2014, title={Evaluating the Curie-Weiss Temperature of a Magnetic System Composed of Nonequivalent Magnetic Ions in Terms of Spin Exchange Constants}, volume={35}, ISSN={["1229-5949"]}, DOI={10.5012/bkcs.2014.35.5.1277}, abstractNote={E-mail: mike_whangbo@ncsu.eduReceived January 18, 2014, Accepted February 5, 2014Key Words : Nonequivalent magnetic ions, Curie-Weiss temperature, Mean field theory, Spin exchange pa-rameters, Density functional theory Magnetic properties of a system containing magnetic ionsare related to its electronic structure,}, number={5}, journal={BULLETIN OF THE KOREAN CHEMICAL SOCIETY}, author={Lee, Kee Hag and Lee, Ji Young and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2014}, month={May}, pages={1277–1278} }
 @article{lee_hong_whangbo_shim_2013, title={Enhancing the Thermoelectric Properties of Layered Transition-Metal Dichalcogenides 2H-MQ(2) (M = Mo, W; Q = S, Se, Te) by Layer Mixing: Density Functional Investigation}, volume={25}, ISSN={["1520-5002"]}, DOI={10.1021/cm402281n}, abstractNote={We explored how to improve the thermoelectric properties of the layered transition-metal dichalcogenides 2H-MQ2 (M = Mo, W; Q = S, Se, Te) by comparing the thermoelectric properties of hypothetical mixed-layer systems 2H-MQ2/2H-MQ′2, in which two different layers 2H-MQ2 and 2H-MQ′2 (Q, Q′ = S, Se, Te) alternate, with those of their pure components on the basis of density functional calculations. Our study predicts that the mixed-layer compounds MS2/MTe2 (M = Mo, W) strongly enhance the thermoelectric properties as a consequence of reducing the band gap and the interlayer van der Waals interactions. The layer-mixing is predicted to be a promising way of improving the thermoelectric properties of 2H-MQ2.}, number={18}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Changhoon and Hong, Jisook and Whangbo, Myung-Hwan and Shim, Ji Hoon}, year={2013}, month={Sep}, pages={3745–3752} }
 @article{xiang_lee_koo_gong_whangbo_2013, title={Magnetic properties and energy-mapping analysis}, volume={42}, ISSN={["1477-9234"]}, DOI={10.1039/c2dt31662e}, abstractNote={The magnetic energy levels of a given magnetic solid are closely packed in energy because the interactions between magnetic ions are weak. Thus, in describing its magnetic properties, one needs to generate its magnetic energy spectrum by employing an appropriate spin Hamiltonian. In this review article we discuss how to determine and specify a necessary spin Hamiltonian in terms of first principles electronic structure calculations on the basis of energy-mapping analysis and briefly survey important concepts and phenomena that one encounters in reading the current literature on magnetic solids. Our discussion is given on a qualitative level from the perspective of magnetic energy levels and electronic structures. The spin Hamiltonian appropriate for a magnetic system should be based on its spin lattice, i.e., the repeat pattern of its strong magnetic bonds (strong spin exchange paths), which requires one to evaluate its Heisenberg spin exchanges on the basis of energy-mapping analysis. Other weaker energy terms such as Dzyaloshinskii-Moriya (DM) spin exchange and magnetocrystalline anisotropy energies, which a spin Hamiltonian must include in certain cases, can also be evaluated by performing energy-mapping analysis. We show that the spin orientation of a transition-metal magnetic ion can be easily explained by considering its split d-block levels as unperturbed states with the spin-orbit coupling (SOC) as perturbation, that the DM exchange between adjacent spin sites can become comparable in strength to the Heisenberg spin exchange when the two spin sites are not chemically equivalent, and that the DM interaction between rare-earth and transition-metal cations is governed largely by the magnetic orbitals of the rare-earth cation.}, number={4}, journal={DALTON TRANSACTIONS}, author={Xiang, Hongjun and Lee, Changhoon and Koo, Hyun-Joo and Gong, Xingao and Whangbo, Myung-Hwan}, year={2013}, pages={823–853} }
 @article{zhao_hung_li_chen_wu_kremer_banks_simon_whangbo_lee_et al._2012, title={CuBr2-A New Multiferroic Material with High Critical Temperature}, volume={24}, ISSN={["0935-9648"]}, DOI={10.1002/adma.201200734}, abstractNote={A new multiferroic material, CuBr(2) , is reported for the first time. CuBr(2) has not only a high transition temperature (close to liquid nitrogen temperature) but also low dielectric loss and strong magnetoelectric coupling. These findings reveal the importance of anion effects, in the search for the high temperature multiferroics materials among these low-dimensional spin systems.}, number={18}, journal={ADVANCED MATERIALS}, author={Zhao, Li. and Hung, Tsu-Lien and Li, Ching-Chien and Chen, Yang-Yuan and Wu, Maw-Kuen and Kremer, Reinhard K. and Banks, Michael G. and Simon, Arndt and Whangbo, Myung-Hwan and Lee, Changhoon and et al.}, year={2012}, month={May}, pages={2469–2473} }
 @article{meddar_josse_maglione_guiet_la_deniard_decourt_lee_tian_jobic_et al._2012, title={Increasing the Phase-Transition Temperatures in Spin-Frustrated Multiferroic MnWO4 by Mo Doping}, volume={24}, ISSN={["1520-5002"]}, DOI={10.1021/cm2031653}, abstractNote={Ceramic samples of MnW1–xMoxO4 (x ≤ 0.3) solid solution were prepared by a solid-state route with the goal of increasing the magnitude of the spin-exchange couplings among the Mn2+ ions in the spin spiral multiferroic MnWO4. Samples were characterized by X-ray diffraction, optical spectroscopy, magnetization, and dielectric permittivity measurements. It was observed that the Neel temperature TN, the spin spiral ordering temperature TM2, and the ferroelectric phase-transition temperature TFE2 of MnWO4 increased upon the nonmagnetic substitution of Mo6+ for W6+. Like pure MnWO4, the ferroelectric critical temperature TFE2(x) coincides with the magnetic ordering temperature TM2(x). A density functional analysis of the spin-exchange interactions for a hypothetical MnMoO4 that is isostructural with MnWO4 suggests that Mo substitution increases the strength of the spin-exchange couplings among Mn2+ in the vicinity of a Mo6+ ion. Our study shows that the Mo-doped MnW1–xMoxO4 (x ≤ 0.3) compounds are spin-frustrat...}, number={2}, journal={CHEMISTRY OF MATERIALS}, author={Meddar, Lynda and Josse, Michael and Maglione, Mario and Guiet, Amandine and La, Carole and Deniard, Philippe and Decourt, Rodolphe and Lee, Changhoon and Tian, Chuan and Jobic, Stephane and et al.}, year={2012}, month={Jan}, pages={353–360} }
 @article{manson_carreiro_lapidus_stephens_goddard_del sesto_bendix_ghannadzadeh_franke_singleton_et al._2012, title={Influence of HF2- geometry on magnetic interactions elucidated from polymorphs of the metal-organic framework [Ni(HF2)(pyz)(2)]PF6 (pyz = pyrazine)}, volume={41}, number={24}, journal={Dalton Transactions (Cambridge, England : 2003)}, author={Manson, J. L. and Carreiro, K. E. and Lapidus, S. H. and Stephens, P. W. and Goddard, P. A. and Del Sesto, R. E. and Bendix, J. and Ghannadzadeh, S. and Franke, I. and Singleton, J. and et al.}, year={2012}, pages={7235–7243} }
 @article{lee_liu_whangbo_koo_kremer_simon_2012, title={Investigation of the spin exchange interactions and the magnetic structure of the high-temperature multiferroic CuBr2}, volume={86}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.86.060407}, abstractNote={We report a detailed density functional analysis of the spin exchange interactions and the magnetic structure of the high-temperature multiferroic CuBr${}_{2}$ and compare the results with magnetic susceptibility measurements. CuBr${}_{2}$ shows one-dimensional antiferromagnetism and undergoes long-range antiferromagnetic ordering at $\ensuremath{\sim}$74 K. Due to the competition between the nearest- and next-nearest-neighbor spin exchanges, each Cu${}^{2+}$ chain has a cycloidal spin-spiral structure, which is described approximately by a quadrupling of the nuclear cell with spin moment rotation of $\ensuremath{\sim}$${85}^{\ensuremath{\circ}}$ in the plane of the CuBr${}_{2}$ ribbon plane.}, number={6}, journal={PHYSICAL REVIEW B}, author={Lee, C. and Liu, Jia and Whangbo, M. -H. and Koo, H. -J. and Kremer, R. K. and Simon, A.}, year={2012}, month={Aug} }
 @article{tong_koehler_simon_lee_whangbo_2012, title={Optical Properties of the Orchid Colored Silver(II) Fluoride Cs2AgF4}, volume={638}, ISSN={["0044-2313"]}, DOI={10.1002/zaac.201200315}, abstractNote={Abstract}, number={11}, journal={ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE}, author={Tong, Jianwei and Koehler, Juergen and Simon, Arndt and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2012}, month={Sep}, pages={1792–1795} }
 @article{lee_kan_xiang_kremer_lee_hiroi_whangbo_2012, title={Spin Reorientation in the Square-Lattice Antiferromagnets RMnAsO (R = Ce, Nd): Density Functional Analysis of the Spin-Exchange Interactions between the Rare-Earth and Transition-Metal Ions}, volume={51}, ISSN={["1520-510X"]}, DOI={10.1021/ic300685d}, abstractNote={The spin reorientation (SR) phenomenon of the square-lattice antiferromagnets RMnAsO (R = Ce, Nd) was investigated by analyzing the spin-exchange interactions between the rare-earth and the transition-metal ions (R(3+) and Mn(2+), respectively) on the basis of density functional calculations. It is found that the symmetry and strength of the Dzyaloshinskii-Moriya (DM) interaction are determined primarily by the partially filled 4f states of the R(3+) ions and that the DM and biquadratic (BQ) exchanges between the R(3+) and the Mn(2+) ions are unusually strong and control the observed spin reorientation phenomenon. Below their SR temperature, the Mn(2+) and Ce(3+) moments are orthogonal in CeMnAsO but are collinear in NdMnAsO, because the DM interaction dominates over the BQ interaction for CeMnAsO, while the opposite is the case for NdMnAsO. Experiments designed to test the implications of our findings are proposed.}, number={12}, journal={INORGANIC CHEMISTRY}, author={Lee, Changhoon and Kan, Erjun and Xiang, Hongjun and Kremer, Reinhard K. and Lee, Seung-Hun and Hiroi, Zenji and Whangbo, Myung-Hwan}, year={2012}, month={Jun}, pages={6890–6897} }
 @article{lee_kan_whangbo_bussmann-holder_simon_2012, title={Spin/Charge Redistributions and Oxygen Atom Displacements Induced by Spin Flip and Hole Doping in the CuO2 Layer of High-Temperature Superconductors}, volume={25}, ISSN={["1557-1939"]}, DOI={10.1007/s10948-011-1208-3}, number={1}, journal={JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM}, author={Lee, C. and Kan, E. J. and Whangbo, M. -H. and Bussmann-Holder, A. and Simon, A.}, year={2012}, month={Jan}, pages={55–59} }
 @article{manson_baldwin_scott_bendix_del sesto_goddard_kohama_tran_ghannadzadeh_singleton_et al._2012, title={[Ni(HF2)(3-Clpy)(4)]BF4 (py = pyridine): Evidence for spin exchange along strongly distorted F center dot center dot center dot H center dot center dot center dot F- bridges in a one-dimensional polymeric chain}, volume={51}, number={14}, journal={Inorganic Chemistry}, author={Manson, J. L. and Baldwin, A. G. and Scott, B. L. and Bendix, J. and Del Sesto, R. E. and Goddard, P. A. and Kohama, Y. and Tran, H. E. and Ghannadzadeh, S. and Singleton, J. and et al.}, year={2012}, pages={7520–7528} }
 @article{hoch_simon_lee_whangbo_koehler_2011, title={Density functional analysis of the electronic structure of Cs9InO4: Evidence for the presence of a Cs- anion}, volume={226}, ISSN={["2196-7105"]}, DOI={10.1524/zkri.2011.1371}, abstractNote={Abstract The complex oxoindate Cs9InO4, described by the electron counting (Cs+)8Cs—[(In3+)(O2–)4] + 2e−, consists of InO4 tetrahedra and Cs(Cs)16 clusters. In each Cs(Cs)16 cluster a Cs atom is located at the center of the (Cs)16 cage, and the Cs9 sublattice of Cs9InO4 is obtained from the face- and edge-sharing of the Cs(Cs)16 clusters. To examine the charge density distribution among the Cs atoms in each Cs(Cs)16 cluster, density functional calculations were carried out for Cs9InO4, and the results were analyzed. Our analysis indicates that, to a first approximation, the Cs atom located at the center of each Cs(Cs)16 is best described as Cs– anion.}, number={7}, journal={ZEITSCHRIFT FUR KRISTALLOGRAPHIE-CRYSTALLINE MATERIALS}, author={Hoch, Constantin and Simon, Arndt and Lee, Changhoon and Whangbo, Myung-Hwan and Koehler, Juergen}, year={2011}, pages={553–556} }
 @article{lee_lee_park_lee_2011, title={Full Geometry Optimizations of Bond-Stretch Isomers of C-20(2+) Fullerene Dication by the Hybrid Density Functional B3LYP Methods}, volume={32}, ISSN={["0253-2964"]}, DOI={10.5012/bkcs.2011.32.1.277}, abstractNote={were performed using the hybrid density functional (B3LYP/6-31G(d)) methods. All isomers were found to be true minima by frequency analysis at the level of B3LYP/6-31G(d) under the reinforced tight convergence criterion and a pruned (99,590) grid. The zero-point correction energy for the cage bond-stretch isomers was in the increasing order D}, number={1}, journal={BULLETIN OF THE KOREAN CHEMICAL SOCIETY}, author={Lee, Jihyun and Lee, Changhoon and Park, Sung S. and Lee, Kee Hag.}, year={2011}, month={Jan}, pages={277–280} }
 @misc{whangbo_lee_kohler_2011, title={Metal Anions in Metal-Rich Compounds and Polar Intermetallics}, number={26}, journal={European Journal of Inorganic Chemistry}, author={Whangbo, M. H. and Lee, C. and Kohler, J.}, year={2011}, pages={3841–3847} }
 @article{kan_wu_lee_kang_whangbo_2011, title={On the High Magnetic-Ordering Temperature of the 5d Magnetic Oxide Ca3LiOsO6 Crystallizing in a Trigonal Crystal Structure: Density Functional Analysis}, volume={50}, ISSN={["0020-1669"]}, DOI={10.1021/ic200305a}, abstractNote={The 5d magnetic oxide Ca(3)LiOsO(6) has a trigonal arrangement of its LiOsO(6) chains parallel to the c-direction and hence has triangular arrangements of high-spin Os(5+) (d(3)) ions but exhibits no spin frustration and undergoes a long-range antiferromagnetic ordering at a high temperature. The origin of this apparently puzzling observation was examined by evaluating the nearest-neighbor Os-O···O-Os spin exchange interactions of Ca(3)LiOsO(6) on the basis of density functional calculations. Our study shows that, of the two nearest-neighbor interchain spin exchanges, one dominates over the other and that the intrachain spin exchange and the dominating interchain spin exchange are strong and form a three-dimensional antiferromagnetic spin lattice with no spin frustration, which is responsible for the long-range antiferromagnetic ordering of Ca(3)LiOsO(6) at high temperature. In determining the strengths of the Os-O···O-Os exchange interactions of Ca(3)LiOsO(6), the Li(+) and Ca(2+) ions of the O···Li(+)···O and O···Ca(2+)···O linkages are found to play only a minor role.}, number={9}, journal={INORGANIC CHEMISTRY}, author={Kan, Erjun and Wu, Fang and Lee, Changhoon and Kang, Jinhee and Whangbo, Myung-Hwan}, year={2011}, month={May}, pages={4182–4186} }
 @article{musfeldt_liu_li_kang_lee_jena_manson_schlueter_carr_whangbo_2011, title={Pressure-Induced Local Structure Distortions in Cu(pyz)F-2(H2O)(2)}, volume={50}, ISSN={["1520-510X"]}, DOI={10.1021/ic2008039}, abstractNote={We employed infrared spectroscopy along with complementary lattice dynamics and spin density calculations to investigate pressure-driven local structure distortions in the copper coordination polymer Cu(pyz)F(2)(H(2)O)(2). Here, pyz is pyrazine. Our study reveals rich and fully reversible local lattice distortions that buckle the pyrazine ring, disrupt the bc-plane O-H···F hydrogen-bonding network, and reinforce magnetic property switching. The resiliency of the soft organic ring is a major factor in the stability of this material. Interestingly, the collective character of the lattice vibrations masks direct information on the Cu-N and Cu-O linkages through the series of pressure-induced Jahn-Teller axis switching transitions, although Cu-F bond softening is clearly identified above 3 GPa. These findings illustrate the importance of combined bulk and local probe techniques for microscopic structure determination in complex materials.}, number={13}, journal={INORGANIC CHEMISTRY}, author={Musfeldt, J. L. and Liu, Z. and Li, S. and Kang, J. and Lee, C. and Jena, P. and Manson, J. L. and Schlueter, J. A. and Carr, G. L. and Whangbo, M. -H.}, year={2011}, month={Jul}, pages={6347–6352} }
 @article{law_reuvekamp_glaum_lee_kang_whangbo_kremer_2011, title={Quasi-one-dimensional antiferromagnetism and multiferroicity in CuCrO4}, volume={84}, ISSN={["1098-0121"]}, DOI={10.1103/physrevb.84.014426}, abstractNote={The bulk magnetic properties of the new quasi-one-dimensional Heisenberg antiferromagnet, CuCrO${}_{4}$, were characterized by magnetic susceptibility, heat capacity, optical spectroscopy, electron paramagnetic resonance and dielectric capacitance measurements, and density functional evaluations of the intrachain and interchain spin-exchange interactions. We found type-II multiferroicity below the N\'eel temperature of 8.2(5) K, arising from competing antiferromagnetic nearest-neighbor (${J}_{\mathrm{nn}}$) and next-nearest-neighbor (${J}_{\mathrm{nnn}}$) intrachain spin-exchange interactions. Experimental and theoretical results indicate that the ratio ${J}_{\mathrm{nn}}$/${J}_{\mathrm{nnn}}$ is close to 2, putting CuCrO${}_{4}$ in the vicinity of the Majumdar-Ghosh point.}, number={1}, journal={PHYSICAL REVIEW B}, author={Law, J. M. and Reuvekamp, P. and Glaum, R. and Lee, C. and Kang, J. and Whangbo, M. -H. and Kremer, R. K.}, year={2011}, month={Jul} }
 @article{xiang_kan_whangbo_lee_wei_gong_2011, title={Single-ion anisotropy, Dzyaloshinskii-Moriya interaction, and negative magnetoresistance the spin-1/2 pyrochlore R2V2O7}, volume={83}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.83.174402}, abstractNote={semicore level asthe reference, we find that the VBM level of the FM stateis almost the same (only about 0.01 eV higher) as that ofthe AFM state. Therefore the CBM of the AFM state ismuch higher than that of the FM state. The reason why theAFM state has a higher CBM and thus a larger band gap isillustrated in Fig. 3(d). When the spins of two neighboringV ions have an FM coupling, the up-spin}, number={17}, journal={PHYSICAL REVIEW B}, author={Xiang, H. J. and Kan, E. J. and Whangbo, M. -H. and Lee, C. and Wei, Su-Huai and Gong, X. G.}, year={2011}, month={May} }
 @article{manson_lapidus_stephens_peterson_carreiro_southerland_lancaster_blundell_steele_goddard_et al._2011, title={Structural, Electronic, and Magnetic Properties of Quasi-1D Quantum Magnets [Ni(HF2)(pyz)(2)]X (pyz = pyrazine; X = PF6-, SbF6-) Exhibiting Ni-FHF-Ni and Ni-pyz-Ni Spin Interactions}, volume={50}, ISSN={["1520-510X"]}, DOI={10.1021/ic102532h}, abstractNote={[Ni(HF(2))(pyz)(2)]X {pyz = pyrazine; X = PF(6)(-) (1), SbF(6)(-) (2)} were structurally characterized by synchrotron X-ray powder diffraction and found to possess axially compressed NiN(4)F(2) octahedra. At 298 K, 1 is monoclinic (C2/c) with unit cell parameters, a = 9.9481(3), b = 9.9421(3), c = 12.5953(4) Å, and β = 81.610(3)° while 2 is tetragonal (P4/nmm) with a = b = 9.9359(3) and c = 6.4471(2) Å and is isomorphic with the Cu-analogue. Infinite one-dimensional (1D) Ni-FHF-Ni chains propagate along the c-axis which are linked via μ-pyz bridges in the ab-plane to afford three-dimensional polymeric frameworks with PF(6)(-) and SbF(6)(-) counterions occupying the interior sites. A major difference between 1 and 2 is that the Ni-F-H bonds are bent (∼157°) in 1 but are linear in 2. Ligand field calculations (LFT) based on an angular overlap model (AOM), with comparison to the electronic absorption spectra, indicate greater π-donation of the HF(2)(-) ligand in 1 owing to the bent Ni-F-H bonds. Magnetic susceptibility data for 1 and 2 exhibit broad maxima at 7.4 and 15 K, respectively, and λ-like peaks in dχT/dT at 6.2 and 12.2 K that are ascribed to transitions to long-range antiferromagnetic order (T(N)). Muon-spin relaxation and specific heat studies confirm these T(N)'s. A comparative analysis of χ vs T to various 1D Heisenberg/Ising models suggests moderate antiferromagnetic interactions, with the primary interaction strength determined to be 3.05/3.42 K (1) and 5.65/6.37 K (2). However, high critical fields of 19 and 37.4 T obtained from low temperature pulsed-field magnetization data indicate that a single exchange constant (J(1D)) alone is insufficient to explain the data and that residual terms in the spin Hamiltonian, which could include interchain magnetic couplings (J(⊥)), as mediated by Ni-pyz-Ni, and single-ion anisotropy (D), must be considered. While it is difficult to draw absolute conclusions regarding the magnitude (and sign) of J(⊥) and D based solely on powder data, further support offered by related Ni(II)-pyz compounds and our LFT and density-functional theory (DFT) results lead us to a consistent quasi-1D magnetic description for 1 and 2.}, number={13}, journal={INORGANIC CHEMISTRY}, author={Manson, Jamie L. and Lapidus, Saul H. and Stephens, Peter W. and Peterson, Peter K. and Carreiro, Kimberly E. and Southerland, Heather I. and Lancaster, Tom and Blundell, Stephen J. and Steele, Andrew J. and Goddard, Paul A. and et al.}, year={2011}, month={Jul}, pages={5990–6009} }
 @article{manson_warter_schlueter_lancaster_steele_blundell_pratt_singleton_mcdonald_lee_et al._2011, title={[Cu(HF2)(2)(pyrazine)](n): A Rectangular Antiferromagnetic Lattice with a Spin Exchange Path Made Up of Two Different FHF- Bridges}, volume={50}, ISSN={["1521-3773"]}, DOI={10.1002/anie.201006653}, abstractNote={The two-dimensional antiferromagnet [Cu(HF{sub 2}){sub 2}(pyz)]{sub n} (pyz=pyrazine) has a rectangular lattice (see picture) displaying two types of FHF{sup -} bridging modes. The spin exchange through Cu-(FHF){sub 2}-Cu is about 90% stronger than through Cu-pyz-Cu, and the {mu}{sub 1,1}-coordinated FHF{sup -}, which is close in nature to F{sup -}---HF, is largely responsible for the exchange. C black, Cu red, F green, H cyan.}, number={7}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Manson, Jamie L. and Warter, Michelle L. and Schlueter, John A. and Lancaster, Tom and Steele, Andrew J. and Blundell, Stephen J. and Pratt, Francis L. and Singleton, John and McDonald, Ross D. and Lee, Changhoon and et al.}, year={2011}, pages={1573–1576} }
 @article{lee_whangbo_koehler_2010, title={Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T-T)(4-) and Isolated T2- Anions in the Polar Intermetallic Cr5B3-Type Compounds AE(5)T(3) (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn)}, volume={636}, ISSN={["1521-3749"]}, DOI={10.1002/zaac.200900421}, abstractNote={Abstract}, number={1}, journal={ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE}, author={Lee, Changhoon and Whangbo, Myung-Hwan and Koehler, Juergen}, year={2010}, pages={36–40} }
 @article{tian_lee_kan_wu_whangbo_2010, title={Analysis of the Magnetic Structure and Ferroelectric Polarization of Monoclinic MnSb2S4 by Density Functional Theory Calculations}, volume={49}, ISSN={["1520-510X"]}, DOI={10.1021/ic101351b}, abstractNote={Monoclinic MnSb(2)S(4) consists of MnS(4) chains made up of edge-sharing MnS(6) octahedra and adopts a (0, 0.369, 0) magnetic superstructure below 25 K. This ordered magnetic structure, in which the spins of each MnS(4) chain possess a helical spin arrangement, has C(2)' symmetry. On the basis of density functional theory calculations, we explored the origin of the observed noncollinear spin arrangement of MnSb(2)S(4) by evaluating its spin exchanges to find that spin exchanges are frustrated not only within each MnS(4) chain but also between adjacent MnS(4) chains. Our analysis predicts that MnSb(2)S(4) is a multiferroic with a ferroelectric polarization of ∼14 μC/m(2) along the chain direction, and a field-induced reversal of the ferroelectric polarization of MnSb(2)S(4) can occur by reversing the direction of the helical spin rotation in each MnS(4) chain.}, number={23}, journal={INORGANIC CHEMISTRY}, author={Tian, Chuan and Lee, Changhoon and Kan, Erjun and Wu, Fang and Whangbo, Myung-Hwan}, year={2010}, month={Dec}, pages={10956–10959} }
 @article{kan_xiang_wu_lee_yang_whangbo_2010, title={Ferrimagnetism in zigzag graphene nanoribbons induced by main-group adatoms}, volume={96}, number={10}, journal={Applied Physics Letters}, author={Kan, E. and Xiang, H. J. and Wu, F. and Lee, C. and Yang, J. L. and Whangbo, M. H.}, year={2010} }
 @article{tassel_kang_lee_hernandez_qiu_paulus_collet_lake_guidi_whangbo_et al._2010, title={Ferromagnetically Coupled Shastry-Sutherland Quantum Spin Singlets in (CuCl)LaNb2O7}, volume={105}, ISSN={["0031-9007"]}, DOI={10.1103/physrevlett.105.167205}, abstractNote={A thorough crystal structure determination at very low temperature of (CuCl)LaNb₂O₇, originally proposed as a spin-1/2 square-lattice antiferromagnet, is reported thanks to the use of single-crystal x-ray diffraction and powder neutron diffraction. State-of-the-art calculations (maximum entropy method) reveal that (CuCl)LaNb₂O₇ is orthorhombic with Pbam symmetry. First-principles calculations demonstrate that the dominant magnetic interactions are antiferromagnetic between fourth nearest neighbors with a Cu-Cl-Cl-Cu exchange path, which lead to the formation of spin singlets. The two strongest interactions between the singlets are ferromagnetic, which makes (CuCl)LaNb₂O₇ the first system of ferromagnetically coupled Shastry-Sutherland quantum spin singlets.}, number={16}, journal={PHYSICAL REVIEW LETTERS}, author={Tassel, C. and Kang, J. and Lee, C. and Hernandez, O. and Qiu, Y. and Paulus, W. and Collet, E. and Lake, B. and Guidi, T. and Whangbo, M-H and et al.}, year={2010}, month={Oct} }
 @article{tomiyasu_kageyama_lee_whangbo_tsujimoto_yoshimura_taylor_llobet_trouw_kakurai_et al._2010, title={Magnetic excitations in infinite-layer antiferromagnetic insulator}, volume={79}, number={3}, journal={Journal of the Physical Society of Japan}, author={Tomiyasu, K. and Kageyama, H. and Lee, C. and Whangbo, M. H. and Tsujimoto, Y. and Yoshimura, K. and Taylor, J. W. and Llobet, A. and Trouw, F. and Kakurai, K. and et al.}, year={2010} }
 @article{kan_xiang_wu_tian_lee_yang_whangbo_2010, title={Prediction for room-temperature half-metallic ferromagnetism in the half-fluorinated single layers of BN and ZnO}, volume={97}, number={12}, journal={Applied Physics Letters}, author={Kan, E. J. and Xiang, H. J. and Wu, F. and Tian, C. and Lee, C. and Yang, J. L. and Whangbo, M. H.}, year={2010} }
 @article{manson_lancaster_blundell_qiu_singleton_sengupta_pratt_kang_lee_whangbo_2010, title={Spin fluctuations and orbital ordering in quasi-one-dimensional alpha-Cu(dca)(2)(pyz) {dca = dicyanamide = N(CN)(2)(-); pyz = pyrazine}, a molecular analogue of KCuF3}, volume={29}, ISSN={["0277-5387"]}, DOI={10.1016/j.poly.2009.06.063}, abstractNote={The magnetic properties of α-Cu(dca)2(pyz) were examined by magnetic susceptibility, magnetization, inelastic neutron scattering (INS), muon-spin relaxation (μSR) measurements and by first-principles density functional theoretical (DFT) calculations and quantum Monte Carlo (QMC) simulations. The χ versus T curve shows a broad maximum at 3.5 K, and the data between 2 and 300 K is well described by an S = 1/2 Heisenberg uniform chain model with g = 2.152(1) and J/kB = −5.4(1) K. μSR measurements, conducted down to 0.02 K and as a function of longitudinal magnetic field, show no oscillations in the muon asymmetry function A(t). This evidence, together with the lack of spin wave formation as gleaned from INS data, suggests that no long-range magnetic order takes place in α-Cu(dca)2(pyz) down to the lowest measured temperatures. Electronic structure calculations further show that the spin exchange is significant only along the Cu–pyz–Cu chains, such that α-Cu(dca)2(pyz) can be described by a Heisenberg antiferromagnetic chain model. Further support for this comes from the M versus B curve, which is strongly concave owing to the reduced spin dimensionality. α-Cu(dca)2(pyz) is a molecular analogue of KCuF3 owing to dx2-y2 orbital ordering where nearest-neighbor magnetic orbital planes of the Cu2+ sites are orthogonal in the planes perpendicular to the Cu–pyz–Cu chains.}, number={1}, journal={POLYHEDRON}, author={Manson, Jamie L. and Lancaster, Tom and Blundell, Stephen J. and Qiu, Yiming and Singleton, John and Sengupta, Pinaki and Pratt, Francis L. and Kang, Jinhee and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2010}, month={Jan}, pages={514–520} }
 @article{gunaydin-sen_lee_tung_chen_turnbull_landee_wang_whangbo_musfeldt_2010, title={Spin-lattice interactions through the quantum critical transition in Cu(pyz)(NO3)(2)}, volume={81}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.81.104307}, abstractNote={We measured the magnetoinfrared response of the quasi-one-dimensional quantum Heisenberg antiferromagnet $\text{Cu}(\text{pyz}){({\text{NO}}_{3})}_{2}$ to investigate local lattice distortions through the field-driven transition to the fully polarized state. This magnetic quantum critical transition involves changes in the out-of-plane N and C-H bending modes of pyrazine with field that directly track the magnetization. We discuss our findings in terms of calculated spin densities, scaling laws, and extracted spin-phonon coupling constants, the latter of which are large due to the softness of the superexchange ligand.}, number={10}, journal={PHYSICAL REVIEW B}, author={Gunaydin-Sen, O. and Lee, C. and Tung, L. C. and Chen, P. and Turnbull, M. M. and Landee, C. P. and Wang, Y. J. and Whangbo, M. -H. and Musfeldt, J. L.}, year={2010}, month={Mar} }
 @article{lee_park_lee_lee_2010, title={Structure and Energetics of (C-60)(2)(2+) Conformers: Quantum Chemical Studies}, volume={31}, ISSN={["0253-2964"]}, DOI={10.5012/bkcs.2010.31.02.457}, abstractNote={In the point of the isoelectronic view, it is expected that the fullerene cation will have similar properties to those of bora-fullerene. Therefore, it will be interesting to understand the structure and electronic properties of hole doped fullerene di-mer. We previously reported the relative stability of negatively charged fullerene dimer, (C}, number={2}, journal={BULLETIN OF THE KOREAN CHEMICAL SOCIETY}, author={Lee, Changhoon and Park, Sung Soo and Lee, Wang Ro and Lee, Kee Hag}, year={2010}, month={Feb}, pages={457–460} }
 @inproceedings{tong_kremer_kohler_simon_lee_kan_whangbo_2010, title={The layered ferromagnet Cs2AgF4: Antiferromagnetic inter-layer coupling driven by magnetic dipole-dipole interactions}, volume={225}, number={11}, booktitle={Zeitschrift fur Kristallographie}, author={Tong, J. W. and Kremer, R. K. and Kohler, J. and Simon, A. and Lee, C. H. and Kan, E. and Whangbo, M. H.}, year={2010}, pages={498–503} }
 @article{lee_kan_xiang_whangbo_2010, title={Theoretical Investigation of the Magnetic Structure and Ferroelectric Polarization of the Multiferroic Langasite Ba3NbFe3Si2O14}, volume={22}, ISSN={["0897-4756"]}, DOI={10.1021/cm101441p}, abstractNote={The multiferroic langasite Ba3NbFe3Si2O14, crystallizing in a noncentrosymetric space group, has sheets of Fe3+ ions parallel to the ab plane. It adopts a chiral magnetic order below TN = 26 K that has a superstructure with propagation vector (0, 0, ∼1/7). The spin frustration causing this magnetic structure of Ba3NbFe3Si2O14 was examined by evaluating its spin exchange interactions on the basis of density functional calculations and also by calculating its magnetic dipole−dipole interactions. The contribution of the chiral magnetic structure to the ferroelectric polarization of Ba3NbFe3Si2O14 below TN was estimated by Berry phase calculations. The spin exchanges of Ba3NbFe3Si2O14 are frustrated in each //ab sheet and between adjacent sheets of Fe3+ ions. The helical spin rotation along the c axis occurs to minimize the intersheet spin frustration as well as the intersheet magnetic dipole−dipole interactions. The ferroelectric polarization of Ba3NbFe3Si2O14 estimated from calculations is in good agreement...}, number={18}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Changhoon and Kan, Erjun and Xiang, Hongjun and Whangbo, Myung-Hwan}, year={2010}, month={Sep}, pages={5290–5295} }
 @article{tian_kan_lee_whangbo_2010, title={pi-Back-Donation Effect of the Cyanide Ligands on the Electron Correlation and Charge Transfer in Prussian Blue RbMn[Fe(CN)(6)]}, volume={49}, ISSN={["1520-510X"]}, DOI={10.1021/ic902577r}, abstractNote={The temperature-induced charge transfer between the Mn and Fe sites in RbMn[Fe(CN)(6)] was analyzed by density functional theory calculations. Our analysis indicates that the extent of electron correlation (equivalently, the pairing energy or the on-site repulsion) is much greater for the Mn(n+) ion than for the Fe(n+) ion (n = 2, 3). This surprising and counterintuitive finding is a consequence of the pi-back-donation effect of the CN ligands.}, number={7}, journal={INORGANIC CHEMISTRY}, author={Tian, Chuan and Kan, Erjun and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2010}, month={Apr}, pages={3086–3088} }
 @article{manson_stone_southerland_lancaster_steele_blundell_pratt_baker_mcdonald_sengupta_et al._2009, title={Characterization of the Antiferromagnetism in Ag(pyz)(2)(S2O8) (pyz = Pyrazine) with a Two-Dimensional Square Lattice of Ag2+ Ions}, volume={131}, ISSN={["0002-7863"]}, DOI={10.1021/ja9005223}, abstractNote={X-ray powder diffraction and magnetic susceptibility measurements show that Ag(pyz)(2)(S(2)O(8)) consists of 2D square nets of Ag(2+) ions resulting from the corner-sharing of axially elongated AgN(4)O(2) octahedra and exhibits characteristic 2D antiferromagnetism. Nevertheless, mu(+)SR measurements indicate that Ag(pyz)(2)(S(2)O(8)) undergoes 3D magnetic ordering below 7.8(3) K.}, number={13}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Manson, Jamie L. and Stone, Kevin H. and Southerland, Heather I. and Lancaster, Tom and Steele, Andrew J. and Blundell, Stephen J. and Pratt, Francis L. and Baker, Peter J. and McDonald, Ross D. and Sengupta, Pinaki and et al.}, year={2009}, month={Apr}, pages={4590-+} }
 @article{kang_lee_kremer_whangbo_2009, title={Consequences of the intrachain dimer-monomer spin frustration and the interchain dimer-monomer spin exchange in the diamond-chain compound azurite Cu-3(CO3)(2)(OH)(2)}, volume={21}, number={39}, journal={Journal of Physics. Condensed Matter}, author={Kang, J. and Lee, C. and Kremer, R. K. and Whangbo, M. H.}, year={2009} }
 @article{lee_kang_lee_whangbo_2009, title={Density Functional Investigation of the Antiferromagnetic Ordering, Spin Orientation, and Ferroelectric Polarization of Rare-Earth Iron Borate TbFe3(BO3)(4)}, volume={21}, ISSN={["1520-5002"]}, DOI={10.1021/cm9006475}, abstractNote={First-principles density functional calculations were carried out to examine the electronic and magnetic properties of rare-earth iron borate TbFe3(BO3)4. The spin exchange interactions between the Fe3+ (d5, S = 5/2) ions and the preferred orientation of the Tb3+ (f8) spins were evaluated, and the ferroelectric polarization of TbFe3(BO3)4 was calculated. In agreement with experiment, our calculations predict that the spin exchange between the Fe3+ spins is ferromagnetic within each //ab sheet of Fe3+ ions but antiferromagnetic between adjacent //ab sheets of Fe3+ ions, whereas the spin exchange between the Fe3+ and Tb3+ ions within each //ab sheet of Fe3+ and Tb3+ ions is antiferromagnetic. The Tb3+ (f8) ions is found to possess an electron configuration responsible for uniaxial magnetism, hence orienting the Tb3+ spins along the c-direction and leading to the highly anisotropic magnetic susceptibility. The ferroelectric polarization of TbFe3(BO3)4 is largely due to the absence of inversion symmetry of th...}, number={12}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Changhoon and Kang, Jinhee and Lee, Kee Hag and Whangbo, Myung-Hwan}, year={2009}, month={Jun}, pages={2534–2539} }
 @article{kan_xiang_zhang_lee_whangbo_2009, title={Density-functional analysis of spin exchange and ferroelectric polarization in AgCrO2}, volume={80}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.80.104417}, abstractNote={Density-functional calculations were carried out for AgCrO2 to examine its spin exchange and ferroelectric polarization. In the multiferroic state of AgCrO2 the triangular spin lattice of each CrO2 layer forms parallel chains with helical-spin order. The spin exchange interactions of AgCrO2 are strongly frustrated both within and between adjacent CuO2 layers, which gives rise to the observed helical-spin order. The observed ferroelectric polarization of AgCrO2 is not caused by individual helical-spin chains, but by the spiral-spin chain structures that propagate between the helical-spin chains.}, number={10}, journal={PHYSICAL REVIEW B}, author={Kan, E. J. and Xiang, H. J. and Zhang, Y. and Lee, C. and Whangbo, M. -H.}, year={2009}, month={Sep} }
 @article{koo_xiang_lee_whangbo_2009, title={Effect of Magnetic Dipole-Dipole Interactions on the Spin Orientation and Magnetic Ordering of the Spin-Ladder Compound Sr3Fe2O5}, volume={48}, ISSN={["1520-510X"]}, DOI={10.1021/ic9007526}, abstractNote={First-principles density functional theory calculations show that the spin-lattice of Sr(3)Fe(2)O(5) is practically 2D in terms of its spin-exchange interactions. The magnetic dipole-dipole interactions are found to be essential for the 3D magnetic ordering of Sr(3)Fe(2)O(5) at a very low temperature.}, number={19}, journal={INORGANIC CHEMISTRY}, author={Koo, Hyun-Joo and Xiang, Hongjun and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2009}, month={Oct}, pages={9051–9053} }
 @article{dessapt_collet_coue_bujoli-doeuff_jobic_lee_whangbo_2009, title={Kinetics of Coloration in Photochromic Organoammonium Polyoxomolybdates}, volume={48}, ISSN={["1520-510X"]}, DOI={10.1021/ic8013865}, abstractNote={The excellent photochromic properties of (H(2)DABCO)(2)(HDMA)(0.5)Na(0.75)(H(3)O)(0.75)[Mo(8)O(27)] x 3 H(2)O (4), a new member of the (H(2)DABCO)(2)(A)(x)[Mo(8)O(27)] x n H(2)O series, are compared with those of (H(2)DABCO)(2)(NH(4))(2)[Mo(8)O(27)] x 4 H(2)O (1), (H(2)DABCO)(2)(H(2)pipz)[Mo(8)O(27)] (2), and (H(2)pipz)(3)[Mo(8)O(27)] (3). All these powdered materials turn from white to purple under illumination at 365 nm, which is associated with photoreduction of Mo(6+) cations into Mo(5+) cations. We show that the rates of coloration, which increase in the order 1 < 3, 2 < 4, are related to the decrease in the concentration of reducible Mo(6+) centers with irradiation time and follow a second-order reaction law because the event of light absorption at a reducible Mo(6+) site does not necessarily coincide with that of the N(+)-H bond breaking in the N(+)-H...O hydrogen bond associated with the Mo(6+) site. First-principles density functional electronic structure calculations were carried out to find that this trend correlates with the homolytic dissociation energies of the N(+)-H bonds in the organic cations HDMA(+), H(2)pipz(2+), H(2)DABCO(2+), and NH(4)(+). This observation is consistent with a photochromic mechanism based on the homolytic cleavage of N(+)-H bonds rather than on the heterolytic cleavage of N(+)-H bonds.}, number={2}, journal={INORGANIC CHEMISTRY}, author={Dessapt, Remi and Collet, Mathieu and Coue, Violaine and Bujoli-Doeuff, Martine and Jobic, Stephane and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2009}, month={Jan}, pages={574–580} }
 @article{tian_lee_xiang_zhang_payen_jobic_whangbo_2009, title={Magnetic structure and ferroelectric polarization of MnWO4 investigated by density functional calculations and classical spin analysis}, volume={80}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.80.104426}, abstractNote={The ordered magnetic states of MnWO4 at low temperatures were examined by evaluating the spin exchange interactions between the Mn2+ ions of MnWO4 on the basis of first principles density functional calculations and by performing classical spin analysis with the resulting spin exchange parameters. Our work shows that the spin exchange interactions are frustrated within each zigzag chain of Mn2+ ions along the c direction and between such chains of Mn2+ ions along the a direction. This explains the occurrence of a spiral-spin order along the c and a directions in the incommensurate magnetic state AF2, and that of a up arrow up arrow down arrow down arrow spin order along the c and a directions in the commensurate magnetic state AF1. The ferroelectric polarization of MnWO4 in the spiral-spin state AF2 was examined by performing Berry phase calculations for a model superstructure to find that the ferroelectric polarization occurs along the b direction, in agreement with experiment.}, number={10}, journal={PHYSICAL REVIEW B}, author={Tian, Chuan and Lee, Changhoon and Xiang, Hongjun and Zhang, Yuemei and Payen, Christophe and Jobic, Stephane and Whangbo, Myung-Hwan}, year={2009}, month={Sep} }
 @article{musfeldt_vergara_brinzari_lee_tung_kang_wang_schlueter_manson_whangbo_2009, title={Magnetoelastic Coupling through the Antiferromagnet-to-Ferromagnet Transition of Quasi-Two-Dimensional [Cu(HF2)(pyz)(2)]BF4 Using Infrared Spectroscopy}, volume={103}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.103.157401}, abstractNote={We investigated magnetoelastic coupling through the field-driven transition to the fully polarized magnetic state in quasi-two-dimensional [Cu(HF2)(pyz)2]BF4 by magnetoinfrared spectroscopy. This transition modifies out-of-plane ring distortion and bending vibrational modes of the pyrazine ligand. The extent of these distortions increases with the field, systematically tracking the low-temperature magnetization. These distortions weaken the antiferromagnetic spin exchange, a finding that provides important insight into magnetic transitions in other copper halides.}, number={15}, journal={PHYSICAL REVIEW LETTERS}, author={Musfeldt, J. L. and Vergara, L. I. and Brinzari, T. V. and Lee, C. and Tung, L. C. and Kang, J. and Wang, Y. J. and Schlueter, J. A. and Manson, J. L. and Whangbo, M. -H.}, year={2009}, month={Oct} }
 @article{manson_schlueter_funk_southerland_twamley_lancaster_blundell_baker_pratt_singleton_et al._2009, title={Strong H center dot center dot center dot F Hydrogen Bonds as Synthons in Polymeric Quantum Magnets: Structural, Magnetic, and Theoretical Characterization of [Cu(HF2)(pyrazine)(2)]SbF6, [Cu2F(HF)(HF2)(pyrazine)(4)](SbF6)(2), and [CuAg(H3F4)(pyrazine)(5)](SbF6)(2)}, volume={131}, ISSN={["1520-5126"]}, DOI={10.1021/ja808761d}, abstractNote={Three Cu(2+)-containing coordination polymers were synthesized and characterized by experimental (X-ray diffraction, magnetic susceptibility, pulsed-field magnetization, heat capacity, and muon-spin relaxation) and electronic structure studies (quantum Monte Carlo simulations and density functional theory calculations). [Cu(HF(2))(pyz)(2)]SbF(6) (pyz = pyrazine) (1a), [Cu(2)F(HF)(HF(2))(pyz)(4)](SbF(6))(2) (1b), and [CuAg(H(3)F(4))(pyz)(5)](SbF(6))(2) (2) crystallize in either tetragonal or orthorhombic space groups; their structures consist of 2D square layers of [M(pyz)(2)](n+) that are linked in the third dimension by either HF(2)(-) (1a and 1b) or H(3)F(4)(-) (2). The resulting 3D frameworks contain charge-balancing SbF(6)(-) anions in every void. Compound 1b is a defective polymorph of 1a, with the difference being that 50% of the HF(2)(-) links are broken in the former, which leads to a cooperative Jahn-Teller distortion and d(x(2))(-y(2)) orbital ordering. Magnetic data for 1a and 1b reveal broad maxima in chi at 12.5 and 2.6 K and long-range magnetic order below 4.3 and 1.7 K, respectively, while 2 displays negligible spin interactions owing to long and disrupted superexchange pathways. The isothermal magnetization, M(B), for 1a and 1b measured at 0.5 K reveals contrasting behaviors: 1a exhibits a concave shape as B increases to a saturation field, B(c), of 37.6 T, whereas 1b presents an unusual two-step saturation in which M(B) is convex until it reaches a step near 10.8 T and then becomes concave until saturation is reached at 15.8 T. The step occurs at two-thirds of M(sat), suggesting the presence of a ferrimagnetic structure. Compound 2 shows unusual hysteresis in M(B) at low temperature, although chi vs T does not reveal the presence of a magnetic phase transition. Quantum Monte Carlo simulations based on an anisotropic cubic lattice were applied to the magnetic data of 1a to afford g = 2.14, J = -13.4 K (Cu-pyz-Cu), and J(perpendicular) = -0.20 K (Cu-F...H...F-Cu), while chi vs T for 1b could be well reproduced by a spin-1/2 Heisenberg uniform chain model for g = 2.127(1), J(1) = -3.81(1), and zJ(2) = -0.48(1) K, where J(1) and J(2) are the intra- and interchain exchange couplings, respectively, which considers the number of magnetic nearest-neighbors (z). The M(B) data for 1b could not be satisfactorily explained by the chain model, suggesting a more complex magnetic structure in the ordered state and the need for additional terms in the spin Hamiltonian. The observed variation in magnetic behaviors is driven by differences in the H...F hydrogen-bonding motifs.}, number={19}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Manson, Jamie L. and Schlueter, John A. and Funk, Kylee A. and Southerland, Heather I. and Twamley, Brendan and Lancaster, Tom and Blundell, Stephen J. and Baker, Peter J. and Pratt, Francis L. and Singleton, John and et al.}, year={2009}, month={May}, pages={6733–6747} }
 @article{park_lee_jung_jung_2009, title={Structure related photocatalytic properties of TiO2}, volume={30}, number={2}, journal={Bulletin of the Korean Chemical Society}, author={Park, J. Y. and Lee, C. and Jung, K. W. and Jung, D.}, year={2009}, pages={402–404} }
 @article{lee_kang_lee_whangbo_2009, title={Symmetry-Dependent Strong Reduction of the Spin Exchange Interactions in Cs2CuCl4 by the 6p Orbitals of Cs+ Ions}, volume={48}, ISSN={["1520-510X"]}, DOI={10.1021/ic802412x}, abstractNote={Despite a three-dimensional arrangement of its CuCl(4)(2-) ions, the magnetic properties of Cs(2)CuCl(4) are explained by a two-dimensional frustrated triangular antiferromagnetic spin-lattice. The origin of this low-dimensional magnetism was explored by evaluating the spin exchange interactions of A(2)CuCl(4) (A = Cs, Rb, K, Na) on the basis of first principles density functional calculations. The calculated spin exchange parameters agree with experiment only when the Cs(+) ions located between the CuCl(4)(2-) ions are not neglected. The antiferromagnetic spin exchange interaction between adjacent CuCl(4)(2-) ions is strongly reduced by the 6p orbitals of the intervening Cs(+) ions when the arrangement of the CuCl(4)(2-) and Cs(+) ions has either mirror-plane or inversion symmetry. The observed magnetism of Cs(2)CuCl(4) arises from this symmetry-dependent participation of the 6p orbitals of the Cs(+) ions in the spin exchange interactions between CuCl(4)(2-) ions.}, number={9}, journal={INORGANIC CHEMISTRY}, author={Lee, Changhoon and Kang, Jinhee and Lee, Kee Hag and Whangbo, Myung-Hwan}, year={2009}, month={May}, pages={4165–4170} }
 @article{lee_lee_kang_park_hwang_lee_2009, title={Uptake effects of two electrons for relative stability and atomic structures of carbon cluster isomers of C-20: ab initio methods}, volume={30}, number={2}, journal={Bulletin of the Korean Chemical Society}, author={Lee, W. R. and Lee, C. and Kang, J. and Park, S. S. and Hwang, Y. G. and Lee, K. H.}, year={2009}, pages={445–448} }
 @article{lee_whangbo_koehler_2008, title={Analysis of electronic structures and chemical bonding of metal-rich compounds. I. Density functional study of Pt metal, LiPt2, LiPt, and Li2Pt}, volume={29}, ISSN={["1096-987X"]}, DOI={10.1002/jcc.21020}, abstractNote={Abstract}, number={13}, journal={JOURNAL OF COMPUTATIONAL CHEMISTRY}, author={Lee, Changhoon and Whangbo, Myung-Hwan and Koehler, Juergen}, year={2008}, month={Oct}, pages={2154–2160} }
 @article{liu_dronskowski_kremer_ahrens_lee_whangbo_2008, title={Characterization of the magnetic and structural properties of copper carbodiimide, CuNCN, by neutron diffraction and first-principles evaluations of its spin exchange interactions}, volume={112}, ISSN={["1932-7447"]}, DOI={10.1021/jp8007199}, abstractNote={The crystal structure of copper carbodiimide, CuNCN, was determined from neutron diffraction data at room temperature and at 4 K, and the electrical resistivity, specific heat, and magnetic susceptibility measurements were carried out. The spin exchange interactions of CuNCN were evaluated by performing first-principles density functional theory electronic structure calculations. CuNCN is a semiconductor containing Jahn−Teller distorted CuN6 octahedra around the divalent copper ions, and the material shows a very small and almost temperature-independent magnetic susceptibility. Our electronic structure calculations evidence that the spin exchange interactions of CuNCN are dominated by two antiferromagnetic spin exchange paths leading to a triangular lattice antiferromagnet within the ab plane. Because the coupling between the layers (along the c axis) is small, CuNCN may be regarded a two-dimensional S = 1/2 frustrated triangular Heisenberg quantum antiferromagnet.}, number={29}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Liu, Xiaohui and Dronskowski, Richard and Kremer, Reinhard K. and Ahrens, Martin and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2008}, month={Jul}, pages={11013–11017} }
 @article{angst_hermann_christianson_lumsden_lee_whangbo_kim_ryan_nagler_tian_et al._2008, title={Charge Order in LuFe2O4: Antiferroelectric Ground State and Coupling to Magnetism}, volume={101}, ISSN={["0031-9007"]}, DOI={10.1103/physrevlett.101.227601}, abstractNote={X-ray scattering by multiferroic LuFe2O4 is reported. Below 320 K, superstructure reflections indicate an incommensurate charge order with propagation close to (1/3 1/3 3/2). The corresponding charge configuration, also found by electronic structure calculations as most stable, contains polar Fe/O double layers with antiferroelectric stacking. Diffuse scattering at 360 K, with (1/3 1/3 0) propagation, indicates ferroelectric short-range correlations between neighboring double layers. The temperature dependence of the incommensuration indicates that charge order and magnetism are coupled.}, number={22}, journal={PHYSICAL REVIEW LETTERS}, author={Angst, M. and Hermann, R. P. and Christianson, A. D. and Lumsden, M. D. and Lee, C. and Whangbo, M. -H. and Kim, J. -W. and Ryan, P. J. and Nagler, S. E. and Tian, W. and et al.}, year={2008}, month={Nov} }
 @article{manson_conner_schlueter_mcconnell_southerland_malfant_lancaster_blundell_brooks_pratt_et al._2008, title={Experimental and Theoretical Characterization of the Magnetic Properties of CuF2(H2O)(2)(pyz) (pyz = pyrazine): A Two-Dimensional Quantum Magnet Arising from Supersuperexchange Interactions through Hydrogen Bonded Paths}, volume={20}, ISSN={["1520-5002"]}, DOI={10.1021/cm8016566}, abstractNote={The structural, electronic, and magnetic properties of the new linear chain coordination polymer CuF2(H2O)2(pyz) (pyz = pyrazine) were determined by single crystal X-ray diffraction at various temperatures, SQUID magnetometry, pulsed-field magnetization, ESR, muon-spin relaxation (μSR), and electronic structure calculations. Each Cu2+ ion of CuF2(H2O)2(pyz) is located at a distorted CuF2O2N2 octahedron with axial elongation along the Cu−N bonds. These octahedra are tethered together by strong F···H−O hydrogen bonds to yield two-dimensional (2D) square nets in the bc-plane that are linked along the a-direction by pyrazine linkages. Measurements of the g-factor by ESR along with first principles density functional theory electronic structure calculations show that the magnetic orbital of the Cu2+ ion lies in the CuF2O2 plane thus forming a 2D antiferromagnetic square lattice. A broad maximum observed in χ(T) at 10 K indicates a modest spin exchange interaction through the Cu−F···H−O−Cu supersuperexchange pa...}, number={24}, journal={CHEMISTRY OF MATERIALS}, author={Manson, Jamie L. and Conner, Marianne M. and Schlueter, John A. and McConnell, Amber C. and Southerland, Heather I. and Malfant, Isabelle and Lancaster, Tom and Blundell, Stephen J. and Brooks, Michael L. and Pratt, Francis L. and et al.}, year={2008}, month={Dec}, pages={7408–7416} }
 @article{chan_lee_dai_whangbo_ibers_2008, title={On the anisotropy of the magnetic properties of CsYbZnSe3}, volume={47}, ISSN={["1520-510X"]}, DOI={10.1021/ic701961f}, abstractNote={DC magnetic susceptibility measurements on CsYbZnSe 3 show a broad magnetic transition at approximately 10 K and pronounced differences between zero-field-cooled and field-cooled data that lead to experimental effective magnetic moments of 4.26(5) BM and 4.39(4) BM, respectively. Specific heat measurements confirm that there is neither long-range ordering nor a phase transition between 1.8 and 380 K. First-principles electronic structure calculations with and without inclusion of spin-orbit coupling effects show that the spins of CsYbZnSe 3 prefer to orient along [010] rather than along either [100] or [001] of this orthorhombic material and that the spin exchange between adjacent Yb3+ ions along [100] is substantially antiferromagnetic. The magnetic properties of CsYbZnSe 3 are best described by an Ising uniform antiferromagnetic chain model.}, number={5}, journal={INORGANIC CHEMISTRY}, author={Chan, George H. and Lee, Changhoon and Dai, Dad and Whangbo, Myung-Hwan and Ibers, James A.}, year={2008}, month={Mar}, pages={1687–1692} }
 @article{kabbour_janod_corraze_danot_lee_whangbo_cario_2008, title={Structure and magnetic properties of oxychalcogenides A(2)F(2)Fe(2)OQ(2) (A = sr, ba; Q = s, se) with Fe2O square planar layers representing an antiferromagnetic checkerboard spin lattice}, volume={130}, ISSN={["1520-5126"]}, DOI={10.1021/ja711139g}, abstractNote={The oxychalcogenides A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se), which contain Fe2O square planar layers of the anti-CuO2 type, were predicted using a modular assembly of layered secondary building units and subsequently synthesized. The physical properties of these compounds were characterized using magnetic susceptibility, electrical resistivity, specific heat, (57)Fe Mossbauer, and powder neutron diffraction measurements and also by estimating their exchange interactions on the basis of first-principles density functional theory electronic structure calculations. These compounds are magnetic semiconductors that undergo a long-range antiferromagnetic ordering below 83.6-106.2 K, and their magnetic properties are well-described by a two-dimensional Ising model. The dominant antiferromagnetic spin exchange interaction between S = 2 Fe(2+) ions occurs through corner-sharing Fe-O-Fe bridges. Moreover, the calculated spin exchange interactions show that the A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se) compounds represent a rare example of a frustrated antiferromagnetic checkerboard lattice.}, number={26}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Kabbour, Houria and Janod, Etienne and Corraze, Benoit and Danot, Michel and Lee, Changhoon and Whangbo, Myung-Hwan and Cario, Laurent}, year={2008}, month={Jul}, pages={8261–8270} }
 @article{xiang_lee_whangbo_2007, title={Absence of a spiral magnetic order in Li2CuO2 containing one-dimensional CuO2 ribbon chains}, volume={76}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.76.220411}, abstractNote={On the basis of first principles density functional theory electronic structure calculations as well as classical spin analysis, we explored why the magnetic oxide Li2CuO2, consisting of CuO2 ribbon chains made up of edge-sharing CuO4 squares, does not exhibit a spiral-magnetic order. Our work shows that, due to the next-nearest-neighbor interchain interactions, the observed collinear magnetic structure becomes only slightly less stable than the spin-spiral ground state, and many states become nearly degenerate in energy with the observed collinear structure. This suggests that the collinear magnetic structure of Li2CuO2 is a consequence of order-by-disorder induced by next-nearest-neighbor interchain interactions.}, number={22}, journal={PHYSICAL REVIEW B}, author={Xiang, H. J. and Lee, C. and Whangbo, M. -H.}, year={2007}, month={Dec} }
 @article{koehler_friedrich_lee_whangbo_2007, title={IrIn7GeO8=[IrIn6](GeO4)(InO4) and compounds of the solid solution series [IrIn6](Ge1+xIn1-4x/O-3(8)) (0 <= x <= 0.75): First oxides containing [IrIn6] octahedra}, volume={633}, ISSN={["1521-3749"]}, DOI={10.1002/zaac.200700126}, abstractNote={Abstract}, number={9}, journal={ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE}, author={Koehler, Juergen and Friedrich, Holger A. and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2007}, pages={1464–1471} }
 @article{lee_whangbo_villesuzanne_2007, title={On the electronic structure required for the uniaxial magnetic properties of the magnetic metal SrCo6O11}, volume={19}, ISSN={["1520-5002"]}, DOI={10.1021/cm0706191}, abstractNote={On the basis of electronic structure analysis, it is shown that the total moment of SrCo6O11 per formula unit should be close to 6 μB, rather than 4 μB reported experimentally, to explain its uniaxial magnetic properties.}, number={11}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Changhoon and Whangbo, Myung-Hwan and Villesuzanne, Antoine}, year={2007}, month={May}, pages={2712–2714} }
 @article{lee_dieckmann_lee_whangbo_2007, title={Predicting anisotropic electrical conductivities of a magnetic insulator on the basis of its magnetic properties}, volume={19}, ISSN={["1520-5002"]}, DOI={10.1021/cm071481p}, abstractNote={Our analysis of the spin exchange interactions and the anisotropic electrical conductivities of the orthosilicate, fayalite Fe2SiO4 indicates that the anisotropic electrical conductivities of a magnetic insulator can be predicted on the basis of its spin exchange parameters and Ohm's law.}, number={18}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Kee Hag and Dieckmann, Ruediger and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2007}, month={Sep}, pages={4393–4395} }
 @article{ben yahia_gaudin_lee_whangbo_darriett_2007, title={Structural and magnetic properties of a new type of ordered oxygen-deficient perovskite, KMnVO4}, volume={19}, ISSN={["1520-5002"]}, DOI={10.1021/cm070452b}, abstractNote={A new ternary vanadate KMnVO4 was prepared by a solid-state reaction and was shown to be a new type of ordered oxygen-deficient perovskite ABO3 - δ with δ = 1/3. Its formula can be rewritten as (K2,Mn)[Mn,V2]O8□1. An ordered distribution of potassium and manganese atoms in the A site and of vanadium and manganese atoms in the B site is observed. The manganese atoms are in distorted octahedral and tetrahedral sites, whereas all of the vanadium atoms form VO43- tetrahedra. This oxide contains four different types of high-spin Mn2+ ions in equal number. Magnetic susceptibility and specific heat measurements as well as spin dimer analysis show that substantial antiferromagnetic spin-exchange interactions occur primarily among three of the four different types of Mn2+ ions, and the fourth Mn2+ ion remains paramagnetic down to 2 K.}, number={23}, journal={CHEMISTRY OF MATERIALS}, author={Ben Yahia, H. and Gaudin, E. and Lee, C. and Whangbo, M. -H. and Darriett, J.}, year={2007}, month={Nov}, pages={5563–5569} }
 @article{lee_whangbo_koehler_2007, title={Stuffed graphite-like vs. stuffed diamond-like structures of the 18 valence electron compounds REAuSn (RE = sc, y, la-nd, sm, gd-lu)}, volume={633}, ISSN={["0044-2313"]}, DOI={10.1002/zaac.200700317}, abstractNote={Abstract}, number={15}, journal={ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE}, author={Lee, Changhoon and Whangbo, Myung-Hwan and Koehler, Juergen}, year={2007}, pages={2631–2634} }