An average fock operator technique of approximate open-shell LCAO-MO-SCF calculation

Bhattacharyya, Sankar Prasad ; Chowdhury, Mihir (1981) An average fock operator technique of approximate open-shell LCAO-MO-SCF calculation Proceedings of the Indian Academy of Sciences - Chemical Sciences, 90 (5). pp. 391-405. ISSN 0253-4134

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Official URL: http://www.ias.ac.in/j_archive/chemsci/90/vol90con...

Related URL: http://dx.doi.org/10.1007/BF02880851

Abstract

The exchange part of the usual Hartree-Fock potential in the unrestricted Hartree-Fock (UHF) theory is suitablyaveraged to construct an, average one-electron model Hamiltonian which generates a set of spin-restricted one-electron orbitals in a self-consistent manner. These orbitals are then used to calculate the electronic energy of the open-shell system by using the proper functional form for the energy which handles the exchange terms correctly. The eigenvalues of Fav can be used for calculating either the spin-polarised or spin-averaged ionisation potentials of different orbitals at theKoopmans' theorem level of approximation. Comparison of E ac with the UHF-energy shows thatE UHF<E ac in each case revealing some kind of an upper bound nature of E ac. An approximate variational argument is given. Relationship of our model with the hyper-Hartree-Fock theory of slater is explored and the general problem of eliminating 'self-interaction' terms in average Fock-operator based theories is discussed.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Average Fock Operator; Approximate Open-shell Theories; Half-electron Method; Hyper-hartree Fock Model
ID Code:3199
Deposited On:11 Oct 2010 09:59
Last Modified:04 Apr 2012 10:20

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