A new generation of effective core potentials: Selected lanthanides and heavy elements II

TL;DR

This paper introduces a new set of correlation-consistent effective core potentials for heavy elements, optimized for accuracy and transferability in materials science and chemistry applications, especially in relativistic and correlated systems.

Contribution

The paper develops and validates a novel set of ccECPs for selected heavy elements, combining relativistic effects and correlation considerations for improved accuracy.

Findings

Achieves chemical accuracy in bond energies and lengths.

Demonstrates excellent agreement with all-electron calculations.

Validates transferability across molecular systems.

Abstract

We present a new set of correlation-consistent effective core potentials (ccECPs) for selected heavy $s$, $p$, $d$, and $f$-block elements significant in materials science and chemistry (Rb, Sr, Cs, Ba, In, Sb, Pb, Ru, Cd, La, Ce, and Eu). The ccECPs are designed using minimal Gaussian parameterization to achieve smooth and bounded potentials. They are expressed as a combination of averaged relativistic effective potentials (AREP) and effective spin-orbit (SO) terms, developed within a relativistic coupled-cluster framework. The optimization is driven by correlated all-electron (AE) atomic spectra, norm-conservation, and spin-orbit splittings, with considerations for plane wave cut-offs to ensure accuracy and viability across various electronic configurations. Transferability of these ccECPs is validated through testing on molecular oxides and hydrides, emphasizing discrepancies in molecular binding energies across a spectrum of bond lengths and electronic environments. The ccECPs demonstrate excellent agreement with AE reference calculations, attaining chemical accuracy in bond dissociation energies and equilibrium bond lengths, even in systems characterized by substantial relativistic and correlation effects. These ccECPs provide accurate and transferable framework for valence-only calculations.