Question

Quantum Physics Question:

What is the difference between electronic exchange and correlation? How can we obtain exchange energy exactly? How best can you obtain the correlation energy?

Answer 1

Electronic exchange is the process in which an electron with the same spin-exchange their positions in degenerate orbitals in the same shell, the exchange energy is the energy released when the electrons switch positions. Electronic correlation is an interaction between electrons in quantum system where the motion of one of the electrons will affect the other electrons. Correlation energy is the measure of how much the movement of one electron will influence the other electron.

Correlation energy can be calculated by calculating the true energy and the Hartree Fork energy and then taking a difference between them. The exchange energy can be calculated by using DFT studies, and by using Bloch states.