Accurate atomic correlation and total energies for correlation consistent effective core potentials II: Rb-Xe elements

TL;DR

This paper benchmarks correlation-consistent effective core potentials (ccECPs) for Rb-Xe elements using advanced correlated methods, providing accurate total energies and validating their effectiveness for many-body electronic structure calculations.

Contribution

It introduces comprehensive benchmark data for ccECPs with various correlated methods, enhancing the accuracy of valence-only Hamiltonians for heavy elements.

Findings

ccECPs yield highly accurate total energies across methods

Benchmark data validate ccECPs for Rb-Xe elements

Fixed-node bias data improve QMC reliability

Abstract

We employ correlation-consistent effective core potentials (ccECPs) to perform exact or nearly exact correlation and total energy calculations for the fifth-row elements (Rb-Xe). Total energies are calculated using various correlated methods: configuration interaction (CI), coupled-cluster (CC) up to perturbative quadruple excitations whenever feasible, and stochastic quantum Monte Carlo (QMC) approaches. In order to estimate the energy at the complete basis set (CBS) limit, the basis sets are constructed systematically through aug-cc-p(C)VnZ for each ccECP and further extrapolated to the CBS limit within the corresponding methods. Kinetic energies are evaluated at the FCI/CISD level to provide insights into the electron density and localization of the ccECPs. We also provide data sets for widely used diffusion Monte Carlo (DMC) to quantify fixed-node biases with single-reference trial wavefunctions. These comprehensive benchmarks validate the accuracy of ccECPs within the CC, CI, and QMC methodologies, thus providing accurate and tested valence-only Hamiltonians for many-body electronic structure calculations.