A BCS APPROACH TO MOLECULAR CORRELATION

摘要

A new method is proposed for calculating the ground-state energy and the corresponding electronic correlation energy of molecules with an even number of electrons. A transformation of single-electron terms of the Hamiltonian into terms of the double-electron type and the application of the Hartree-Fock-Bogolyubov variational principle to the new equivalent Hamiltonian are presented. A Bardeen-Cooper-Schrieffer-type ansatz is used for the molecular wave function in analogy with the description of superconductivity in metals. Some test calculations on the ground state of several molecules show the goodness of this method. (C) 1995 John Wiley & Sons, Inc. [References: 28]