CLUSTER MODEL FOR THE ELECTRONIC STRUCTURES OF COMPLEX MOLECULES AND SOLIDS

K. Johnson

A cluster model has been developed for calculating from first principles the electronic structures of complex molecules and solids. In this model, attention is focused on a particular cluster of atoms which may be an entire molecule, part of a larger molecule, or part of an ordered or disordered crystal. The cluster is geometrically partitioned into contiguous atomic, interatomic, and extrarnolecular regions. The self-consistent-field Schrödinger equation is set up in each region for a model Hartree-Fock potential including Slater's Xε statistical approximation to exchange correlation, and the problem is solved via scattered-wave formalism somewhat similar to that developed originally by Korringa. The effects of the particular environment are described by boundary conditions on the cluster, e. g. the matching of the solutions of Schrödinger's equation in the extramolecular region to the solutions in the atomic and interatomic regions at an artificial spherical boundary surrounding the entire cluster. No explicit use is made of Bloch's theorem, unless through the introduction of periodic boundary conditions on the cluster. Illustrative applications of the model to be described include : (1) self-consistent-field spin-unrestricted calculations on transition-metal complexes ; (2) large-cluster calculations of deep impurity levels in semiconductors ; and (3) calculations of the chemical bonding of the biologically active prosthetic groups of certain metallo-enzymes and proteins. Computer generated contour maps of the electronic wavefunctions and charge densities illustrating the chemical bonds in various clusters are also presented.

Domaines: Articles anciens

K. Johnson. CLUSTER MODEL FOR THE ELECTRONIC STRUCTURES OF COMPLEX MOLECULES AND SOLIDS. Journal de Physique Colloques, 1972, 33 (C3), pp.C3-195-C3-203. ⟨10.1051/jphyscol:1972329⟩. ⟨jpa-00215063⟩