Journal ArticleDOI
MCSCF reference quasidegenerate perturbation theory with Epstein—Nesbet partitioning
TLDR
A quasidegenerate perturbation theory (QDPT) with Epstein-Nesbet partitioning based on MCSCF reference functions is presented in this paper, where the formulas for CSF-based matrix operations are derived.About:
This article is published in Chemical Physics Letters.The article was published on 1993-05-28. It has received 259 citations till now. The article focuses on the topics: Perturbation theory.read more
Citations
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Journal ArticleDOI
The construction and interpretation of MCSCF wavefunctions.
TL;DR: The multiconfiguration self-consistent field method offers the most general approach to the computation of chemical reactions and multiple electronic states and localized orbitals are convenient both for selection of the appropriate active space and for understanding the computed results.
Journal ArticleDOI
Extended multi-configuration quasi-degenerate perturbation theory: the new approach to multi-state multi-reference perturbation theory.
TL;DR: The efficient implementation strategy that makes XMCQDPT2 an especially useful general-purpose tool in the high-level modeling of small to large molecular systems is described.
Journal ArticleDOI
Third-order multireference perturbation theory The CASPT3 method
TL;DR: In this article, Rayleigh-Schrodinger perturbation theory is applied to compute second and third-order correlation energies using complete active space self-consistent field (CASSCF) zeroth-order wavefunctions.
Journal ArticleDOI
OpenMolcas : From Source Code to Insight
Ignacio Fdez. Galván,Morgane Vacher,Ali Alavi,Celestino Angeli,Francesco Aquilante,Jochen Autschbach,Jie J. Bao,Sergey I. Bokarev,Nikolay A. Bogdanov,Rebecca K. Carlson,Liviu F. Chibotaru,Joel Creutzberg,Joel Creutzberg,Nikesh S. Dattani,Mickaël G. Delcey,Sijia S. Dong,Andreas Dreuw,Leon Freitag,Luis Manuel Frutos,Laura Gagliardi,Frédéric Gendron,Angelo Giussani,Angelo Giussani,Leticia González,Gilbert Grell,Meiyuan Guo,Chad E. Hoyer,Marcus Johansson,Sebastian Keller,Stefan Knecht,Goran Kovačević,Erik Källman,Giovanni Li Manni,Marcus Lundberg,Yingjin Ma,Sebastian Mai,João Pedro Malhado,Per-Åke Malmqvist,Philipp Marquetand,Stefanie A. Mewes,Stefanie A. Mewes,Jesper Norell,Massimo Olivucci,Massimo Olivucci,Massimo Olivucci,Markus Oppel,Quan Manh Phung,Kristine Pierloot,Felix Plasser,Markus Reiher,Andrew M. Sand,Igor Schapiro,Prachi Sharma,Christopher J. Stein,Lasse Kragh Sørensen,Donald G. Truhlar,Mihkel Ugandi,Liviu Ungur,Alessio Valentini,Steven Vancoillie,Valera Veryazov,Oskar Weser,Tomasz Adam Wesolowski,Per-Olof Widmark,Sebastian Wouters,Alexander Zech,J. Patrick Zobel,Roland Lindh +67 more
TL;DR: The OpenMolcas environment is described and features unique to simulations of spectroscopic and magnetic phenomena such as the exact semiclassical description of the interaction between light and matter, various X-ray processes, magnetic circular dichroism and properties are described.
Journal ArticleDOI
Multiconfigurational nuclear-electronic orbital approach: Incorporation of nuclear quantum effects in electronic structure calculations
TL;DR: The nuclear-electronic orbital (NEO) method for the calculation of mixed nuclearelectronic wave functions is presented in this article, where both electronic and nuclear molecular orbitals are expressed as linear combinations of Gaussian basis functions.
References
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Journal ArticleDOI
Gaussian Basis Functions for Use in Molecular Calculations. III. Contraction of (10s6p) Atomic Basis Sets for the First‐Row Atoms
TL;DR: In this paper, the effects of contraction on the energies and one-electron properties of the water and nitrogen molecules were investigated, and the authors obtained principles which can be used to predict optimal contraction schemes for other systems without the necessity of such exhaustive calculations.
Journal ArticleDOI
Second-order perturbation theory with a complete active space self-consistent field reference function.
TL;DR: In this paper, the Fock-type one-electron operator was extended by allowing the zeroth-order Hamiltonian to have nonzero elements also in nondiagonal matrix blocks.
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Second-order perturbation theory with a CASSCF reference function
TL;DR: In this article, the second-order perturbation theory based on a CASSCF reference state is derived and implemented, where the first-order wave function includes the full space of interacting states and the zeroth-order Hamiltonian reduces to the MOller-Plesset Hamiltonian for a closed shell reference state.
Journal ArticleDOI
Multireference Møller-Plesset method
TL;DR: In this paper, a multireference Moller-Plesset method is derived for 2-configuration MCSCF wavefunctions in which only two electrons are correlated, and potential curves for H 2, HF and F 2 molecules agree well with the full or near-full CI results.
Journal ArticleDOI
Multireference Møller—Plesset perturbation theory for high-spin open-shell systems
TL;DR: In this paper, new forms of multireference Moller-Plesset perturbation theory are presented that are applicable to high-spin open-shell systems and results are reported for the energy difference between the 1 A 1 and 3 B 1 states of CH 2 and for the potential energy curve of the triplet ground state (3 Σ − g ) of O 2.