# Shape and Energy Consistent Pseudopotentials for Correlated Electron systems

## TL;DR

This paper introduces energy consistent correlated-electron pseudopotentials (eCEPPs) that improve the accuracy of molecular geometries and dissociation energies in correlated-electron calculations, outperforming previous pseudopotentials.

## Contribution

The paper develops a novel method combining shape and energy consistency for generating pseudopotentials tailored for correlated-electron systems, with demonstrated accuracy improvements.

## Key findings

- eCEPPs significantly improve molecular geometry predictions.
- Dissociation energy errors are an order of magnitude smaller than previous pseudopotentials.
- Validated with coupled cluster calculations on various elements.

## Abstract

A method is developed for generating pseudopotentials for use in correlated-electron calculations. The paradigms of shape and energy consistency are combined and defined in terms of correlated-electron wave-functions. The resulting energy consistent correlated electron pseudopotentials (eCEPPs) are constructed for H, Li--F, Sc--Fe, and Cu. Their accuracy is quantified by comparing the relaxed molecular geometries and dissociation energies they provide with all electron results, with all quantities evaluated using coupled cluster singles doubles and triples calculations. Errors inherent in the pseudopotentials are also compared with those arising from a number of approximations commonly used with pseudopotentials. The eCEPPs provide a significant improvement in optimised geometries and dissociation energies for small molecules, with errors for the latter being an order-of-magnitude smaller than for Hartree-Fock-based pseudopotentials available in the literature. Gaussian basis sets are optimised for use with these pseudopotentials.