On optimal values of alpha for the analytic Hartree-Fock-Slater method

TL;DR

This paper investigates the optimal alpha parameter in the Hartree-Fock-Slater method, demonstrating that a specific value significantly improves atomization energy predictions compared to other methods.

Contribution

The study empirically determines the optimal alpha value for the HFS method, enhancing its accuracy over traditional local density and Hartree-Fock approaches.

Findings

Optimal alpha (0.7091) reduces MAE to 14 kcal/mol

HFS with optimal alpha outperforms LDA and Hartree-Fock in atomization energies

Use of this alpha may aid in developing better exchange-correlation functionals

Abstract

We have examined the performance of the analytic Hartree-Fock-Slater (HFS) method for various alpha (Slater's exchange parameter) values and empiricaly determined the optimal alpha value by minimizing the mean absolute error (MAE) in atomization energies of the G2 set of molecules. At the optimal alpha the HFS method's performance is far superior with the MAE of 14 kcal/mol than that of the local density approximation (MAE ~ 36 kcal/mol) or the Hartree-Fock theory (MAE ~ 78 kcal/mol). The HFS exchange functional with alpha = 0.7091 is found to perform significantly better than the Kohn-Sham exchange functional for equally weighted atoms H-Kr. We speculate that use of this alpha value may be useful in parametrization of empirical exchange-correlation functionals.