Dear Robert, I am not familiar with the method for applying an
exchange correlation. But is this applied by using perturbation on the
Hamiltonian of the multi/electron system, that is a perturbation Hamiltonian
which applied the effect from the
exchange?
THanks Sergio From: ownerchemistry**ccl.net To: sergio.manzetti**gmx.com Subject: CCL: Exchange correlation Date: Thu, 12 Jun 2014 21:31:49 0400 No. The exchange refers to the energy penalty for antisymmetrization of the wavefunction. It is a permutation operator (K) applied to the Coulomb operator (J). It is not enough to have Coulombic repulsion; QM dictates that no two fermions have the same quantum state. If you want to work with fermions, you have to represent a penalty toward having the same quantum state. Correlation is an extended euphemism to mean "everything you do not get from the restrictions placed on the wavefunction in restricted HartreeFock theory." The term more precisely derives from the fact that the joint probability distribution function of the oneparticle reduced density matrix shows that the there is no statistical correlation between two orbitals and their density...hence the term "correlation." On 06/12/2014 07:05 PM, William
McDonald pchem==ucsc.edu wrote:
