Complete active space self-consistent fields coupled-cluster theory

Complete Active Space Self-Consistent Field Coupled-Cluster Theory... 

SM calculations are broadly based on either the (i) Hartree-Fock method (ii) Post-Hartree-Fock methods like the Mpller-Plesset level of theory (MP), configuration interaction (Cl), complete active space self-consistent field (CASSCF), coupled cluster singles and doubles (CCSD) or (iii) methods based on DFT [24-27]. Since the inclusion of electron correlation is vital to obtain an accurate description of nearly all the calculated properties, it is desirable that SM calculations are carried out at either the second-order Mpller-Plesset (MP2) or the coupled cluster with single, double, and perturbative triple substitutions (CCSD(T)) levels using basis sets composed of both diffuse and polarization functions. 

ACES II Anharmonic Molecular Force Fields Bench-mark Studies on Small Molecules Complete Active Space Self-consistent Field (CASSCF) Second-order Perturbation Theory (CASPT2) Configuration Interaction Core-Valence Correlation Effects Coupled-cluster Theory Density Functional Theory (DFT), Hartree-Fock (HF), and the Self-consistent Field G2 Theory Heats of Formation Hybrid Methods Hydrogen Bonding 1 M0ller-Plesset Perturbation Theory NMR Data Correlation with Chemical Structure Photochemistry Proton Affinities r 2 Dependent Wave-functions Rates of Chemical Reactions Reaction Path Following Reaction Path Hamiltonian and its Use for Investigating Reaction Mechanisms Spectroscopy Computational... 

Extended articles on the most common electron correlation methods such as limited configuration interaction (Cl see Configuration Interaction), M0ller-Plesset many-body perturbation theory (MBPT see M0ller Plesset Perturbation Theory), variation-perturbation methods (such as PCILO see Complete Active Space Self-consistent Field (CASSCF) Second-order Perturbation Theory (CASPT2) and Configuration Interaction), and coupled cluster theory (CC see Coupled-cluster Theory), as well as on explicitly ri2-dependent wave functions (see rxi Dependent Wave functions), can be found elsewhere. 

An in-depth description of the theoretical basis of these methodologies as well as other computational techniques can be found in Refs. [5,8]. The dynamic correlation energy can be efficiently recovered by using the Cl (configurational interaction), Mpller-Plesset perturbation theory (MP ), and coupled cluster (CC) methods, whereas multireference Cl methods such as complete active space self-consistent field (CASSCF) allow an adequate description of the static correlations. 

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