Towards Verifying Exact Conditions for Implementations of Density Functional Approximations

TL;DR

This paper introduces XCVerifier, a novel tool that verifies whether density functional approximations in DFT implementations satisfy known exact conditions, enhancing reliability and correctness in computational chemistry.

Contribution

XCVerifier is the first formal verification approach for checking if DFA implementations meet the theoretical exact conditions in DFT.

Findings

Successfully verified or identified violations in multiple DFA implementations.

Demonstrated feasibility of formal methods for verifying DFT functionals.

Applied to five DFAs from Libxc and seven exact conditions.

Abstract

Density Functional Theory (DFT) is used extensively in the computation of electronic properties of matter, with various applications. Approximating the exchange-correlation (XC) functional is the key to the Kohn-Sham DFT approach, the basis of most DFT calculations. The choice of this density functional approximation (DFA) depends crucially on the particular system under study, which has resulted in the development of hundreds of DFAs. Though the exact density functional is not known, researchers have discovered analytical properties of this exact functional. Furthermore, these exact conditions are used when designing DFAs. We present XCVerifier, the first approach for verifying whether a DFA implementation satisfies the DFT exact conditions. XCVerifier was evaluated on five DFAs from the popular Libxc library and seven exact conditions from recent work. XCVerifier was able to verify or find violations for a majority of the DFA/condition pairs, demonstrating the feasibility of using formal methods to verify DFA implementations.