Optimized Effective Potentials in Finite Basis Sets

TL;DR

This paper investigates the finite basis optimized effective potential method in density functional theory, identifying issues with unbalanced basis sets and proposing a regularized functional to ensure physical, well-balanced potentials.

Contribution

It introduces a regularizing functional that guides the selection of balanced basis sets and improves the physicality of OEP calculations in finite basis sets.

Findings

Unbalanced basis sets lead to nonphysical potentials.

A regularized functional improves potential quality.

Method to select optimal OEP potential and energy.

Abstract

The finite basis optimized effective potential (OEP) method within density functional theory is examined as an ill-posed problem. It is shown that the generation of nonphysical potentials is a controllable manifestation of the use of unbalanced, and thus unsuitable, basis sets. A modified functional incorporating a regularizing smoothness measure of the OEP is introduced. This provides a condition on balanced basis sets for the potential, as well as a method to determine the most appropriate OEP potential and energy from calculations performed with any finite basis set.