@article{kwon_curtin_morrow_kelley_jakubikova_2023, title={Adaptive basis sets for practical quantum computing}, volume={4}, ISSN={["1097-461X"]}, url={https://doi.org/10.1002/qua.27123}, DOI={10.1002/qua.27123}, abstractNote={AbstractElectronic structure calculations on small systems such as H2, H2O, LiH, and BeH2 with chemical accuracy are still a challenge for the current generation of noisy intermediate‐scale quantum (NISQ) devices. One of the reasons is that due to the device limitations, only minimal basis sets are commonly applied in quantum chemical calculations, which allows one to keep the number of qubits employed in the calculations at a minimum. However, the use of minimal basis sets leads to very large errors in the computed molecular energies as well as potential energy surface shapes. One way to increase the accuracy of electronic structure calculations is through the development of small basis sets better suited for quantum computing. In this work, we show that the use of adaptive basis sets, in which exponents and contraction coefficients depend on molecular structure, provides an easy way to dramatically improve the accuracy of quantum chemical calculations without the need to increase the basis set size and thus the number of qubits utilized in quantum circuits. As a proof of principle, we optimize an adaptive minimal basis set for quantum computing calculations on an H2 molecule, in which exponents and contraction coefficients depend on the HH distance, and apply it to the generation of H2 potential energy surface on IBM‐Q quantum devices. The adaptive minimal basis set reaches the accuracy of the double‐zeta basis sets, thus allowing one to perform double‐zeta quality calculations on quantum devices without the need to utilize twice as many qubits in simulations. This approach can be extended to other molecular systems and larger basis sets in a straightforward manner.}, journal={INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY}, author={Kwon, Hyuk-Yong and Curtin, Gregory M. M. and Morrow, Zachary and Kelley, C. T. and Jakubikova, Elena}, year={2023}, month={Apr} }
@article{curtin_jakubikova_2022, title={Extended pi-Conjugated Ligands Tune Excited-State Energies of Iron(II) Polypyridine Dyes}, volume={11}, ISSN={["1520-510X"]}, url={https://doi.org/10.1021/acs.inorgchem.2c02362}, DOI={10.1021/acs.inorgchem.2c02362}, abstractNote={Over the past decade, iron(II) polypyridines have gained a lot of attention as potential chromophores and sensitizers due to the low cost and high abundance of iron. Unfortunately, most iron(II) polypyridines are poor chromophores since their initially excited, photoactive metal-to-ligand charge transfer (MLCT) states quickly decay into non-photoactive metal-centered (MC) states. Many strategies to increase their lifetime have been pursued, built mainly around increasing the ligand field strength of these complexes and thus destabilizing the MC states. In this work, we aim to design a new class of Fe(II) complexes by stabilizing the energies of their MLCT states. To this end, we employ density functional theory (DFT) and time-dependent DFT to investigate a series of Fe(II) complexes, [Fe(L/X)2,4(N^N)]2+/2- where L/X represents either cyanide, isocyanide, or bipyridine ligands and N̂N stands for bidentate-extended π-conjugated ligands derived from the bipyridine. The L/X ligands tune the energetics of the Fe-based t2g molecular orbitals, while the amount of π-conjugation on the N^N ligand impacts the energies of its π and π* orbitals, thus tuning the energetics of the MLCT and the ligand-centered (LC) states. Overall, our results suggest that the use of N^N ligands with the extended π-conjugation is a viable strategy to tune the relative energies of MLCT, LC, and MC states.}, journal={INORGANIC CHEMISTRY}, author={Curtin, Gregory M. and Jakubikova, Elena}, year={2022}, month={Nov} }
@article{turner_breen_kosgei_crandall_curtin_jakubikova_ryan m. o'donnell_ziegler_rack_2022, title={Manipulating Excited State Properties of Iridium Phenylpyridine Complexes with ?Push-Pull? Substituents}, volume={11}, ISSN={["1520-510X"]}, url={https://doi.org/10.1021/acs.inorgchem.2c02269}, DOI={10.1021/acs.inorgchem.2c02269}, abstractNote={We have prepared a series of complexes of the type [IrIII(ppy)2(L]n+ complexes (1-4), where ppy is a substituted 2-phenylpyridine and L is a chelating phosphine thioether ligand. The parent complex (1) comprises an unsubstituted phenylpyridine ligand, whereas complex 2 contains a nitro substituent on the pyridine ring, complex 3 features a diphenylamine group on the phenyl ring, and 4 has both nitro and diphenylamine groups. Crystallographic, 1H NMR, and elemental analysis data are consistent with each of the chemical formulae. DFT (density functional theory) computational results show a complicated electronic structure with contributions from Ir, ppy, and the PS ligand. Ultrafast pump-probe data show strong contributions from the phenylpyridine moieties as well as strong panchromatic excited state absorption transitions. The data show that nitro and/or diphenylamine substituents dominate the spectroscopy of this series of compounds.}, journal={INORGANIC CHEMISTRY}, author={Turner, Emigdio E. and Breen, Douglas J. and Kosgei, Gilbert and Crandall, Laura A. and Curtin, Gregory M. and Jakubikova, Elena and Ryan M. O'Donnell and Ziegler, Christopher J. and Rack, Jeffrey J.}, year={2022}, month={Nov} }
@article{marshburn_ashley_curtin_sultana_liu_vinueza_ison_jakubikova_2021, title={Are all charge-transfer parameters created equally? A study of functional dependence and excited-state charge-transfer quantification across two dye families}, volume={8}, ISSN={["1463-9084"]}, url={https://doi.org/10.1039/D1CP03383B}, DOI={10.1039/d1cp03383b}, abstractNote={Twenty dyes from the Max Weaver Dye Library were used to benchmark six commonly used DFT functionals to understand the interplay between the errors in the calculated excitation energies and the degree of charge transfer character of the excitations.}, journal={PHYSICAL CHEMISTRY CHEMICAL PHYSICS}, publisher={Royal Society of Chemistry (RSC)}, author={Marshburn, Richard Drew and Ashley, Daniel C. and Curtin, Gregory M. and Sultana, Nadia and Liu, Chang and Vinueza, Nelson R. and Ison, Elon A. and Jakubikova, Elena}, year={2021}, month={Aug} }
@article{labrum_curtin_jakubikova_caulton_2020, title={The Influence of Nucleophilic and Redox Pincer Character as well as Alkali Metals on the Capture of Oxygen Substrates: The Case of Chromium(II)}, volume={26}, ISSN={["1521-3765"]}, url={https://doi.org/10.1002/chem.202000457}, DOI={10.1002/chem.202000457}, abstractNote={AbstractDimeric [CrL]2, where L is the conjugate base of bis‐pyrazolyl pyridine, is evaluated for its ability to undergo inner sphere and outer sphere redox chemistry. It reacts with Cp2Fe+ to give [Cr4(HL)4(μ4‐O)]2+, still containing divalent Cr. Reduction (KC8) of [CrL]2 by two electrons gives [K2(THF)3Cr3L3(μ3‐O)], and by four electrons gives [K4(THF)10Cr2L2(μ‐O)], each of which has scavenged (hydr)oxide from glass surface because of the electrophilicity of the underligated Cr. [K4(THF)10Cr2L2(μ‐O)], is shown by comprehensive DFT calculations and analysis of intra‐ligand bond lengths to contain a pyridyl radical L3− and CrII, illustrating that this pincer is proton‐responsive, redox active, and a versatile donor to associated K+ ions here. The K+ electrophiles interact with electron‐rich oxo, but do not significantly (>5 kcal mol−1) alter spin state energies. Inner sphere oxidation of [CrL]2 with a quinone gives [Cr2L2(semiquinone)2], while pre‐reduced [CrL]22− reacts with quinone to give [K3(THF)3Cr2L2(catecholate)2(μ‐OH)], a product of capture of two undercoordinated LCr(catecholate)1− by hydroxide.}, number={43}, journal={CHEMISTRY-A EUROPEAN JOURNAL}, publisher={Wiley}, author={Labrum, Nicholas S. and Curtin, Gregory M. and Jakubikova, Elena and Caulton, Kenneth G.}, year={2020}, month={Aug}, pages={9547–9555} }