Multi-configurational self-consistent fields electronic structure

MCSCF Multi-Configuration Self-Consistent Field. A means of variationally minimizing the energy of several electron configurations of a given system simultaneously, so as to provide a better description of its electronic structure. 

In the RISM-SCF procedure coupled with the multi-configurational self-consistent field (MCSCF) approach [59, 60, 61], the solvent effective potential modifying the electronic structure of the solute molecule is incorporated by adding a solvent term to the Fock operator of an... 

J. Olsen, P. Jprgensen, Time-dependent response theory with applications to self-consistent field and multi-configurational self-consistent field wave functions, in Modern Electronic Structure Theory, Part 11, D. R. Yarkony, Ed., World Scientific, Singapore, 1995, p. 857. 

Core-valence correlation involves the interaction between the inner shell (core) and valence electrons. That this interaction is small is an important axiom of chemistry, as it is well established that the properties of atoms and molecules are largely determined by the valence electrons. This principle underlies the explanation of chemical periodicity and the structure of the periodic table. Conceptually, one considers the inner electrons to be tightly bound and rather inert. Hence, most theoretical studies only consider valence electron correlation with the core electrons frozen at the Hartree-Fock (HF) or multi-configuration self-consistent field (MCSCF) level or replaced with a pseudopotential. The utility and accuracy of the vast body of quantum chemical calculations provide ample evidence justifying this assumption. 

Aspects of the relativistic theory of quantum electrodynamics are first reviewed in the context of the electronic structure theory of atoms and molecules. The finite basis set parametrization of this theory is then discussed, and the formulation of the Dirac-Hartree-Fock-Breit procedure presented with additional detail provided which is specific to the treatment of atoms or molecules. Issues concerned with the implementation of relativistic mean-field methods are outlined, including the computational strategies adopted in the BERTHA code. Extensions of the formalism are presented to include open-shell cases, and the accommodation of some electron correlation effects within the multi-configurational Dirac-Hartree-Fock approximation. We conclude with a survey of representative applications of the relativistic self-consistent field method to be found in the literature. 

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