Electron Correlation: Fermi and Coulomb Holes Dynamical and Nondynamical Correlation

摘要

The independent particle or Hartree Fock (HF) approximation is a much used method in the study of the electronic structure of atoms and molecules. In the calculation of the HF orbitals the instantaneous interaction between the electrons is replaced (approximated) by the interaction of an electron with the average field generated by the other N-1 electrons. The correlation of the electronic movements due to the electronic repulsion (Coulomb correlation) is neglected in the HF approximation. This is the Hartree Fock error or correlation error. In this thesis the correlation problem is studied with the purpose to get a better insight into the shortcomings of the HF model and to get a deeper understanding of electron correlation in a physical and visual manner. Chapter headings are the following: Electron correlation and holes; Analysis of correlation in terms of exact local potentials--Applications to two-electron systems; Analysis of nondynamical correlation in the metal-ligand bond: Pauli repulsion and orbital localization in MnO4(1-); Orbital localization in transition metal molecules; An approximate exchange-correlation hole density as a functional of the one-matrix.