Basis set convergence in extended systems: infinite hydrogen fluoride and hydrogen chloride chains

TL;DR

This study investigates how basis set size affects the accuracy of Hartree-Fock and correlation energy calculations in infinite hydrogen fluoride and hydrogen chloride chains, highlighting the importance of extrapolation methods.

Contribution

It provides a detailed analysis of basis set convergence and demonstrates the effectiveness of extrapolation techniques for extended systems.

Findings

Hartree-Fock energy converges rapidly with basis set size

Correlation energy converges slowly and benefits from extrapolation

Extrapolation significantly improves energy accuracy in extended systems

Abstract

Basis set convergence of the Hartree-Fock and the correlation energy is examined for the hydrogen bonded infinite bent chains (HF)_infinity and (HCl)_infinity. We employ series of correlation consistent basis sets up to quintuple zeta quality together with a coupled cluster method (CCSD) to describe electron correlation on ab initio level. The Hartree-Fock energy converges rapidly with increasing basis set quality whereas the correlation energy is found to be slowly convergent for the same series of basis sets. We study basis set extrapolation for (HF)_infinity and (HCl)_infinity and show that it substantially enhances the accuracy of both the Hartree-Fock and the correlation energy in extended systems.