Investigation of three exchange energy formulas, Hartree–Fock, LDA, and 10/9 LDA

Abstract

Three different formulas for the exchange energy are compared through comprehensive self-consistent calculations on atoms and diatomic molecules. The formulas considered are the Hartree–Fock exchange, the local density approximation (LDA) exchange, and the first order approximation to the new Ghosh–Parr exchange formula which is equivalent to 10/9 LDA. The 10/9 LDA results are vastly superior to the LDA results and comparable or better than the Hartree–Fock results. Possible reasons for this are discussed.