Article
Chemistry, Physical
Michal Lesiuk
Summary: The rank-reduced coupled-cluster theory with single and double excitations achieves substantial amplitude compression with only minor loss of accuracy. The computational costs scale with the system size (N) in a similar way as the conventional CCSD theory, but it can be reduced to N-5 through singular value decomposition for problematic terms. The accuracy of the resulting method is studied for diverse molecules, showing better than 99.9% accuracy with reduced computational costs.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Han Chen, Chris-Kriton Skylaris
Summary: This work extends the energy decomposition analysis (EDA) method to metallic systems for the first time, by considering partially occupied molecular orbitals and using weighted orthogonalization. The method gives more weight to orbitals with higher occupancies and treats each fragment as metallic, providing a new paradigm and tool for studying interactions in metallic systems within large-scale DFT calculations.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Yannick J. Franzke, Jason M. Yu
Summary: We present an exact two-component (X2C) ansatz for the EPRg tensor using gauge-including atomic orbitals (GIAOs) and a magnetically balanced basis set expansion. This implementation results in a gauge-origin-invariant formalism and accurately reproduces the results of the parent four-component relativistic theory. The use of the diagonal local approximation to the unitary decoupling transformation helps reduce computational costs.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
David Mester, Mihaly Kallay
Summary: The DH time-dependent density functional theory is extended to core excitations by introducing two different DH formalisms utilizing the core-valence separation approximation. The performance of the new approaches is tested and compared with the popular CVS-ADC(2) method using a benchmark set. The results show that the genuine approaches are competitive in terms of excitation energies but exhibit significant differences in oscillator strengths.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
David Mester, Mihaly Kallay
Summary: The double-hybrid time-dependent density functional theory is expanded to include core excitations, utilizing the core-valence separation approximation. Two different double-hybrid formalisms are introduced and tested against the XABOOM benchmark set, showing competitive performance in excitation energy calculations but significant differences in oscillator strengths.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Marti Gimferrer, Abdulrahman Aldossary, Pedro Salvador, Martin Head-Gordon
Summary: This study introduces a new method called oxidation state localized orbitals (OSLO) for assigning oxidation states in molecules and evaluating the fragment orbital localization index (FOLI) using an algorithm. The OSLO approach produces satisfactory results in challenging cases and provides new evidence for the emergence of covalent interactions between fragments.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Marcelo T. de Oliveira, Julia M. A. Alves, Ataualpa A. C. Braga, David J. D. Wilson, Cristina A. Barboza
Summary: A benchmark density functional theory study was conducted to assess the performance of DFT methods in calculating H-1 NMR chemical shifts. The results show that currently available double-hybrid DFT methods offer no advantage over GGA functionals in this calculation.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
David Mester, Mihaly Kallay
Summary: In this study, the double-hybrid time-dependent density functional theory is extended to vertical ionization potentials and electron affinities. Efficient implementations are presented for the genuine DH ansatz using the density fitting approximation and perturbative second-order correction. The performance of different DH functionals and other hybrid approaches is assessed in benchmark calculations, and the most accurate and robust functional is found to be the ADC(2)-based SOS-RS-PBE-P86 approach.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Biochemistry & Molecular Biology
Andrzej Eilmes, Piotr Kubisiak, Piotr Wrobel
Summary: This study investigated the influence of two molecular parameters on the reduction potential of ethylene carbonate as a solvent. The results showed that the values of these parameters were inconsistent depending on the solvent model, particularly with the hybrid solvent model yielding estimates closer to the values of an infinite system.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Chemistry, Multidisciplinary
Cameron F. Baker, John A. Seed, Ralph W. Adams, Daniel Lee, Stephen T. Liddle
Summary: This study presents an experimental and computational assessment of two cerium(IV)-diphosphonioalkylidene complexes, confirming the presence of Ce-C double bonds. The research provides quantified benchmarks for understanding diphosphonioalkylidene bonding and reveals the contributions of Ce 4f orbitals and the variance in 4f spin-orbit contributions to the Ce-C bonding.
Article
Computer Science, Interdisciplinary Applications
Honghui Shang, WanZhen Liang, Yunquan Zhang, Jinlong Yang
Summary: A new method for calculating response properties related to atomic displacement and electric field perturbation, based on real-space density-functional perturbation theory (DFPT), has been developed and implemented. The computation bottleneck of the response density matrix has been identified and a more efficient algorithm has been proposed, reducing the formal scaling from O(N-3) to O(N) with good parallel scalability. Validation has shown rapid and accurate computation of polarizabilities using DFPT, with computational efficiency demonstrated on massively parallel computer systems.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Wen-Jie Wei, Per E. M. Siegbahn
Summary: The study suggests that a sulfide might be lost from the active cofactor of nitrogenase during catalysis, with a lower energy barrier compared to other steps. It was also found that there are four activation steps before catalysis starts, and eventually the central carbide will be protonated once. Additionally, a complex transition state for H-2 formation was identified, and a combined step involving the loss of H-2 and binding of N-2 was calculated to be slightly endergonic.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Physical
Daniel S. King, Donald G. Truhlar, Laura Gagliardi
Summary: The selection of active orbitals for modeling strongly correlated electronic states is challenging and highly dependent on the specific states and molecules of interest. The authors propose a discrete variational selection (DVS) approach to tackle this problem by generating multiple trial wave functions from systematically constructed active spaces and choosing the best one variationally. They apply this approach to a database of small-to-medium-sized molecules and find that it performs well in selecting wave functions based on the energy from multiconfiguration pair-density functional theory.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Jozsef Csoka, Mihaly Kallay
Summary: Several approaches to improve the efficiency of Hartree-Fock and Kohn-Sham self-consistent field calculations have been introduced, utilizing a simple first-order energy correction. The new methods show speedups of up to 80% with minimal loss of accuracy, making them promising for practical applications.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Kevin Curtis, Olajumoke Adeyiga, Olabisi Suleiman, Samuel O. Odoh
Summary: This study demonstrates that the double hybrid density functional approximation omega B88PTPSS, which incorporates the equipartition of density functional theory and the non-local correlation, provides accurate excitation energies for conventional systems and correctly predicts negative singlet-triplet gaps for non-conventional systems without the need for parametric scaling. Furthermore, omega B88PTPSS performs well for open-shell systems and shows excellent agreement with experimental results for real-life examples.
JOURNAL OF CHEMICAL PHYSICS
(2023)
