Theoretical determination of exact-exchange-mixing parameter employing the ionization energy theorem

Abstract

The value of Becke's exact-exchange-mixing parameter is determined by purely theoretical considerations by requiring that the ionization energy theorem (−ϵm=I) be satisfied as closely as possible. This method is applied to the case in which the density functional theory approximation to the exchange–correlation energy functional is given by the local spin density approximation with Perdew–Zunger self-interaction correction, which leads to the correct−1/r long-range behavior of the exchange– correlation potential and consequently to accurate highest occupied orbital energy eigenvalues, ϵm. Employing this approach on atoms with Z≤20 self-consistent optimized-effective potential calculations results in the determination of the mixing parameter, which is in good agreement with that of Becke, and the resulting calculations of the ionization potentials and electron affinities for these atoms are on average within 0.10 eV of the experimental results. In addition, the resulting correlation potential for both neon and argon exhibits a positive bump in the region of maximum density of the highest lying p states. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 255–264, 1998