Article
Chemistry, Physical
Emmanouil Semidalas, Jan M. L. Martin
Summary: This study revisited the MOBH35 benchmark and found that multiple methods perform well for low levels of static correlation, but some methods may break down for moderately strong levels of static correlation. The revised reference values differ from the original ones in some reactions. The study provides suggestions for evaluating density functional theory methods and presents diagnostic methods for static correlation.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Emily M. Kempfer-Robertson, Andrew D. Mahler, Meagan N. Haase, Piper Roe, Lee M. Thompson
Summary: The nonorthogonal active space decomposition (NO-ASD) methodology is proposed for systems with multiple correlation mechanisms. It reduces the factorial scaling associated with the size of the correlated orbital space by partitioning the wave function and treating different correlation mechanisms with an effective Hamiltonian approach. Despite its nonorthogonal framework, NO-ASD can take advantage of efficient matrix element evaluation. Comparisons with complete active space methods show that NO-ASD has advantages in reducing problem dimensionality and recovering correlation energy.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Yi-Fan Yao, Wei-Hai Fang, Neil Qiang Su
Summary: The article introduces a method, EBI, to handle the ensemble N-representability constraint by introducing implicit functions. Tests on different systems, initial guesses, and functionals demonstrate the superiority of EBI in handling this constraint.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Physical
Zhigang Ni, Yang Guo, Frank Neese, Wei Li, Shuhua Li
Summary: The paper introduces a cluster-in-molecule (CIM) local correlation approach with an accurate distant pair correlation energy correction, which is crucial for predicting absolute correlation energies and relative energies in large systems. Benchmark calculations demonstrate that the improved CIM approach can recover over 99.94% of the correlation energy calculated by the parent method, providing accurate binding energies for weakly bound complexes of varying sizes.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Qianli Ma, Hans-Joachim Werner
Summary: The study introduces explicitly correlated open-shell pair natural orbital local coupled-cluster methods with additions of explicit correlation and perturbative triples corrections, demonstrating accuracy comparable to canonical calculations within small errors. The use of appropriate approximations can effectively reduce computational complexity while maintaining accuracy in challenging cases.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Ruhee D'Cunha, T. Daniel Crawford
Summary: By incorporating a fixed number of orbitals from the pair natural orbital (PNO) space into the PNO++ method, the accuracy in CCSD correlation energy is recovered while maintaining the well-behaved convergence behavior of the PNO++ method for linear response properties.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
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
Robert Izsak
Summary: The local implementation of the similarity-transformed equation of motion-coupled cluster method allows for efficient and accurate calculation of excitation energies and properties for large molecular systems. This method has been shown to deliver accurate results and can be applied to a variety of large systems.
INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY
(2021)
Article
Chemistry, Physical
Moritz Bensberg, Johannes Neugebauer
Summary: In this study, a pair-selected multi-level DLPNO-CCSD (T-0) approach is proposed to accurately calculate the changes in correlation energy between orbital pairs in chemical reactions. This method is more robust than previous approaches and more efficient without adding complexity or sacrificing accuracy.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Ruhee D'Cunha, T. Daniel Crawford
Summary: In this study, the efficacy of two variations of the pair-natural-orbital approach, namely PNO++ and combined PNO++, were investigated for reducing the scaling in coupled cluster property calculations. The results showed that for different types of molecules, the truncation errors in response properties were similar for all three methods, while the PNO method performed slightly better than the PNO++ and combined PNO++ methods in terms of correlation energies.
Article
Chemistry, Physical
Jerzy Cioslowski, Krzysztof Strasburger
Summary: The symmetry equiincidence principle quantifies the apportionment of natural orbitals among the irreducible representations of a point group, but it fails for certain groups.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Sarai Dery Folkestad, Eirik F. Kjonstad, Linda Goletto, Henrik Koch
Summary: Efficient implementations of MLCC2 and MLCCSD models are presented in this study, with the ability to handle large molecular systems and reduce computational costs, combined with a reduced-space approach to significantly decrease storage requirements.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Ahmet Altun, Christoph Riplinger, Frank Neese, Giovanni Bistoni
Summary: The domain-based local pair natural orbital coupled-cluster method with singles, doubles, and perturbative triples (DLPNO-CCSD(T)) has been successful in accurately computing energies and properties of large and complex systems. However, it faces challenges when applied to first-row transition metals with a complex electronic structure. This study addresses the errors caused by semicore correlation effects and dynamic correlation-induced orbital relaxation (DCIOR) effects, proposing strategies to eliminate these errors and improve the method's efficiency.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Artur Nowak, Ors Legeza, Katharina Boguslawski
Summary: Wave functions based on electron-pair states provide reliable models for describing quantum many-body problems with strongly correlated electrons, especially when broken-pair states are corrected appropriately. The study analyzes the performance of electron-pair methods in predicting orbital-based correlation spectra, focusing on the pCCD-LCC ansatz. It is found that pCCD-LCC accurately reproduces orbital-pair correlation patterns in weak correlation limits and for molecules close to their equilibrium structure.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Yuqi Wang, Zhigang Ni, Frank Neese, Wei Li, Yang Guo, Shuhua Li
Summary: The PBC-CIM method is extended with the DLPNO approach to reduce computational costs, allowing accurate descriptions of periodic systems. The method is applied to optimize lattice parameters and investigate adsorption problems, showing accurate and efficient results.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Qianli Ma, Hans-Joachim Werner
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2019)
Article
Chemistry, Physical
Christine Krause, Hans-Joachim Werner
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2019)
Article
Chemistry, Physical
Mark Dornbach, Hans-Joachim Werner
Article
Chemistry, Physical
Yuri Alexandre Aoto, Arne Bargholz, Daniel Kats, Hans-Joachim Werner, Andreas Koehn
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2019)
Article
Chemistry, Physical
David A. Kreplin, Peter J. Knowles, Hans-Joachim Werner
JOURNAL OF CHEMICAL PHYSICS
(2019)
Article
Chemistry, Physical
David A. Kreplin, Peter J. Knowles, Hans-Joachim Werner
JOURNAL OF CHEMICAL PHYSICS
(2020)
Article
Chemistry, Physical
Peter Pulay, Hans-Joachim Werner
Article
Chemistry, Physical
L. F. Pasteka, T. Helgaker, T. Saue, D. Sundholm, H. -J. Werner, M. Hasanbulli, J. Major, P. Schwerdtfeger
Article
Chemistry, Physical
Hans-Joachim Werner, Peter J. Knowles, Frederick R. Manby, Joshua A. Black, Klaus Doll, Andreas Hesselmann, Daniel Kats, Andreas Koehn, Tatiana Korona, David A. Kreplin, Qianli Ma, Thomas F. Miller, Alexander Mitrushchenkov, Kirk A. Peterson, Iakov Polyak, Guntram Rauhut, Marat Sibaev
JOURNAL OF CHEMICAL PHYSICS
(2020)
Article
Chemistry, Physical
Qianli Ma, Hans Joachim Werner
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2020)
Article
Chemistry, Physical
Qianli Ma, Hans-Joachim Werner
Summary: The study introduces explicitly correlated open-shell pair natural orbital local coupled-cluster methods with additions of explicit correlation and perturbative triples corrections, demonstrating accuracy comparable to canonical calculations within small errors. The use of appropriate approximations can effectively reduce computational complexity while maintaining accuracy in challenging cases.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
David A. Kreplin, Hans-Joachim Werner
Summary: In this work, the optimization of Hartree-Fock orbitals is investigated using the SO-SCI method, which has shown promising results in MCSCF and CASSCF calculations. The method provides faster convergence, avoids saddle-points, and improves convergence in multi-center cases.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Andreas Hesselmann, Hans-Joachim Werner, Peter J. Knowles
Summary: A systematic study on the accuracy and efficiency of various quadrature schemes for molecular Kohn-Sham Density-Functional Theory (DFT) revealed significant differences in accuracies among different approaches, with the new adaptive grid scheme performing the best. Integration errors are shown to be mostly independent of basis sets, with meta-GGA functionals requiring larger integration grids for the same level of accuracy compared to GGA functionals.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Computer Science, Interdisciplinary Applications
M. H. Alexander, P. J. Dagdigian, H. -J. Werner, J. Klos, B. Desrousseaux, G. Raffy, F. Lique
Summary: Hibridon is a program package that solves the close-coupled equations in the quantum treatment of inelastic atomic and molecular collisions. It can handle various types of collisions and photodissociation processes and calculate cross sections and amplitudes. The program is capable of treating closed-shell and open-shell systems.
COMPUTER PHYSICS COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Philipp P. Hallmen, Hans-Joachim Werner, Daniel Kats, Samuel Lenz, Guntram Rauhut, Hermann Stoll, Joris van Slageren
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2019)