@article{zhang_whangbo_2011, title={Density Functional Analysis of the Spin Exchange Interactions and Charge Order Patterns in the Layered Magnetic Oxides YBaM2O5 (M = Mn, Fe, Co)}, volume={50}, ISSN={["0020-1669"]}, DOI={10.1021/ic200963g}, abstractNote={The spin and charge order phenomena of the layered magnetic oxides YBaM(2)O(5) (M = Mn, Fe, Co) were analyzed on the basis of density functional calculations. We evaluated the spin exchange interactions of YBaM(2)O(5) by performing energy-mapping analysis based on density functional calculations to find why they undergo a three-dimensional magnetic ordering at high temperature. We estimated the relative stabilities of the checkerboard and stripe charge order patterns of YBaM(2)O(5) (M = Mn, Fe, Co) by optimizing their structures with density functional calculations to probe if the nature of the charge order pattern depends on whether their transition-metal ions are Jahn-Teller active.}, number={21}, journal={INORGANIC CHEMISTRY}, author={Zhang, Yuemei and Whangbo, Myung-Hwan}, year={2011}, month={Nov}, pages={10643–10647} }
 @article{zhang_kan_whangbo_2011, title={Density Functional Investigation of the Difference in the Magnetic Structures of the Layered Triangular Antiferromagnets CuFeO2 and AgCrO2}, volume={23}, ISSN={["1520-5002"]}, DOI={10.1021/cm2011567}, abstractNote={The layered triangular antiferromagnets CuFeO2 and AgCrO2 exhibit ferroelectric polarization when they adopt a helical spiral-spin magnetic structure. Application of magnetic field parallel to the c-axis or doping Fe sites with Al or Ga is necessary for CuFeO2 to have a helical spiral spin order. However, AgCrO2 adopts a helical spiral spin order in the absence of such extrinsic factors. A probable cause for this difference between the two systems was examined by evaluating the relative stabilities of their helical spiral and collinear spin structures on the basis of density functional calculations. In contrast to the case of AgCrO2, the collinear ↑↑↓↓ state is only slightly higher in energy than the helical spiral-spin state Qa+b in CuFeO2 so that extrinsic factors such as oxygen vacancy and applied magnetic field can influence whether CuFeO2 adopts the ↑↑↓↓ or Qa+b structure.}, number={18}, journal={CHEMISTRY OF MATERIALS}, author={Zhang, Yuemei and Kan, Erjun and Whangbo, Myung-Hwan}, year={2011}, month={Sep}, pages={4181–4185} }
 @article{zhang_kan_xiang_villesuzanne_whangbo_2011, title={Density Functional Theory Analysis of the Interplay between Jahn-Teller Instability, Uniaxial Magnetism, Spin Arrangement, Metal-Metal Interaction, and Spin-Orbit Coupling in Ca3CoMO6 (M = Co, Rh, Ir)}, volume={50}, ISSN={["0020-1669"]}, DOI={10.1021/ic1022278}, abstractNote={In the isostructural oxides Ca(3)CoMO(6) (M = Co, Rh, Ir), the CoMO(6) chains made up of face-sharing CoO(6) trigonal prisms and MO(6) octahedra are separated by Ca atoms. We analyzed the magnetic and electronic properties of these oxides on the basis of density functional theory calculations including on-site repulsion and spin-orbit coupling, and examined the essential one-electron pictures hidden behind results of these calculations. Our analysis reveals an intimate interplay between Jahn-Teller instability, uniaxial magnetism, spin arrangement, metal-metal interaction, and spin-orbit coupling in governing the magnetic and electronic properties of these oxides. These oxides undergo a Jahn-Teller distortion, but their distortions are weak, so that their trigonal-prism Co(n+) (n = 2, 3) ions still give rise to strong easy-axis anisotropy along the chain direction. As for the d-state split pattern of these ions, the electronic and magnetic properties of Ca(3)CoMO(6) (M = Co, Rh, Ir) are consistent with d(0) < (d(2), d(-2)) < (d(1), d(-1)) but not with (d(2), d(-2)) < d(0) < (d(1), d(-1)). The trigonal-prism Co(3+) ion in Ca(3)Co(2)O(6) has the L = 2 configuration (d(0))(1)(d(2), d(-2))(3)(d(1), d(-1))(2) because of the metal-metal interaction between adjacent Co(3+) ions in each Co(2)O(6) chain, which is mediated by their z(2) orbitals, and the spin-orbit coupling of the trigonal-prism Co(3+) ion. The spins in each CoMO(6) chain of Ca(3)CoMO(6) prefer the ferromagnetic arrangement for M = Co and Rh but the antiferromagnetic arrangement for M = Ir. The octahedral M(4+) ion of Ca(3)CoMO(6) has the (1a)(1)(1e)(4) configuration for M = Rh but the (1a)(2)(1e)(3) configuration for M = Ir, which arises from the difference in the spin-orbit coupling of the M(4+) ions and the Co···M metal-metal interactions.}, number={5}, journal={INORGANIC CHEMISTRY}, author={Zhang, Yuemei and Kan, Erjun and Xiang, Hongjun and Villesuzanne, Antoine and Whangbo, Myung-Hwan}, year={2011}, month={Mar}, pages={1758–1766} }
 @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{zhang_xiang_whangbo_2009, title={Interplay between Jahn-Teller instability, uniaxial magnetism, and ferroelectricity in Ca3CoMnO6}, volume={79}, ISSN={["1098-0121"]}, DOI={10.1103/physrevb.79.054432}, abstractNote={${\text{Ca}}_{3}{\text{CoMnO}}_{6}$ is composed of ${\text{CoMnO}}_{6}$ chains made up of face-sharing ${\text{CoO}}_{6}$ trigonal prisms and ${\text{MnO}}_{6}$ octahedra. The structural, magnetic, and ferroelectric properties of this compound were investigated on the basis of density-functional theory calculations. ${\text{Ca}}_{3}{\text{CoMnO}}_{6}$ is found to undergo a Jahn-Teller distortion associated with the ${\text{CoO}}_{6}$ trigonal prisms containing high-spin ${\text{Co}}^{2+}$ $({d}^{7})$ ions, which removes the ${\text{C}}_{3}$ rotational symmetry and hence uniaxial magnetism. However, the Jahn-Teller distortion is not strong enough to fully quench the orbital moment of the high-spin ${\text{Co}}^{2+}$ ions thereby leading to an electronic state with substantial magnetic anisotropy. The Jahn-Teller distorted ${\text{Ca}}_{3}{\text{CoMnO}}_{6}$ in the magnetic ground state with up-up-down-down spin arrangement is predicted to have electric polarizations much greater than experimentally observed. Implications of the discrepancy between theory and experiment were discussed.}, number={5}, journal={PHYSICAL REVIEW B}, author={Zhang, Y. and Xiang, H. J. and Whangbo, M. -H.}, year={2009}, month={Feb} }
 @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{comins_zhang_joseph_1999, title={Enantiopure N-acyldihydropyridones as synthetic intermediates: Asymmetric synthesis of benzomorphans}, volume={1}, ISSN={["1523-7060"]}, DOI={10.1021/ol990738p}, abstractNote={[formula: see text] Concise asymmetric syntheses of several benzomorphan derivatives have been accomplished using enantiopure 2,3-dihydro-4-pyridones as chiral building blocks.}, number={4}, journal={ORGANIC LETTERS}, author={Comins, DL and Zhang, YM and Joseph, SP}, year={1999}, month={Aug}, pages={657–659} }
 @article{comins_zhang_zheng_1998, title={Photochemical reactions of chiral 2,3-dihydro-4(1H)-pyridones: asymmetric synthesis of (-)-perhydrohistrionicotoxin}, ISSN={["1359-7345"]}, DOI={10.1039/a807448h}, abstractNote={The first chiral auxiliary-mediated asymmetric synthesis of (–)-perhydrohistrionicotoxin is described.}, number={22}, journal={CHEMICAL COMMUNICATIONS}, author={Comins, DL and Zhang, YM and Zheng, XL}, year={1998}, month={Nov}, pages={2509–2510} }
 @article{comins_joseph_hong_alawar_foti_zhang_chen_lamunyon_guerraweltzien_1997, title={Asymmetric synthesis and synthetic utility of 2,3-dihydro-4-pyridones}, volume={69}, ISSN={["0033-4545"]}, DOI={10.1351/pac199769030477}, abstractNote={Abstract}, number={3}, journal={PURE AND APPLIED CHEMISTRY}, author={Comins, DL and Joseph, SP and Hong, H and Alawar, RS and Foti, CJ and Zhang, YM and Chen, XH and LaMunyon, DH and GuerraWeltzien, M}, year={1997}, month={Mar}, pages={477–481} }