Constrained space orbital variation method

M. Dupuis, F. Johnston, and A. Mdrquez, HONDO 8,5 from CHEM-Station , IBM Corporation, King.ston, NY 12401, 1994 A. Mdrquez, J. Rubio, and F. Illas, Implementation of Constrained Space Orbital Variation Method to HONDO 8.5 June... 

The reduced variational space (RVS) method i.s due to Stevens and Fink and is essentially identical to the constrained space orbital variations method of Bagus et al. The... 

The nature of bonding of the adsorbed species to the model cluster of metal surfaces can be analyzed in terms of the so-called constrained space orbital variation (CSOV) method. For halogen anions adsorbed on various silver surfaces, it has been found that Pauli repulsion, metal polarization, and charge transfer to the metal surface mainly contribute to the binding energy of the ions [104, 301]. 

One method that has proven to be particularly useful for the analysis of molecule/surface interactions is the constrained space orbital variation (CSOV) scheme originally proposed by Bagus and Hermann [30,31]. As does the Morokuma scheme, it allows for a decomposition of the total SCF or DFT interaction energy into its different contributions by calculating only energy quantities, and not as do most other decomposition schemes by analyzing electronic densities or wave functions. The CSOV analysis consists of several consecutive steps which can be roughly characterized as follows ... 

Its usefulness in the analysis of bonding in EDA complexes and hydrogen-bonded species notwithstanding, the above scheme has come under criticism on the grounds of its reliance on fictitious wavefunctions that violate the Pauli exclusion principle. Numerous formalisms that do not suffer from this serious conceptual flaw have been put forward. " Neither those foimalisms nor the constrained space orbital variation (CSOV) method, which has been employed in a... 

A particularly useful approach which provides unique information about the importance of different contributions to chemical bonding can be obtained with the constrained space orbital variation (CSOV) method. In this method, constraints are applied to the orbitals that are optimized in the variational procedure and in the space in which the restricted optimization is performed. The restrictions that are applied are based on chemical principles which allow certain types of interactions to occur and prevent others from occurring. The general... 

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