Basis set extrapolation from the vanishing counterpoise correction condition

TL;DR

This paper proposes a novel method for basis set extrapolation in quantum chemistry by using the condition that basis set superposition error (BSSE) should vanish at the complete basis set limit, avoiding traditional analytical or fitting approaches.

Contribution

It introduces a new approach to basis set extrapolation based on BSSE minimization, applicable when basis sets are sufficiently large and balanced.

Findings

BSSE minimization can effectively guide basis set extrapolation.

The method aligns with energy fitting results for unaugmented basis sets.

It offers an alternative to traditional extrapolation techniques.

Abstract

Basis set extrapolations are typically rationalized either from analytical arguments involving the partial-wave or principal expansions of the correlation energy in helium-like systems, or from fitting extrapolation parameters to reference energetics for a small(ish) training set. Seeking to avoid both, we explore a third alternative: extracting extrapolation parameters from the requirement that the BSSE (basis set superposition error) should vanish at the complete basis set limit. We find this to be a viable approach provided that the underlying basis sets are not too small and reasonably well balanced. For basis sets not augmented by diffuse functions, BSSE minimization and energy fitting yield quite similar parameters.