GW100: A Slater Type Orbital Perspective

TL;DR

This paper introduces new Slater Type orbital basis sets for accurate calculation of ionization potentials and electron affinities, demonstrating their effectiveness through comprehensive comparisons with other computational methods.

Contribution

It presents two new Slater Type orbital basis sets of triple- and quadruple-zeta quality, optimized for correlated-electron calculations and electron affinity predictions.

Findings

CBS limit extrapolated IPs agree within 85 meV of other high-level methods.

Electron affinities are accurately predicted with a MAD of 160 meV, especially for molecules with positive LUMOs.

The new basis sets outperform some existing codes in certain cases, providing reliable results for medium to large organic molecules.

Abstract

We calculate complete basis set (CBS) limit extrapolated ionization potentials (IP) and electron affinities (EA) with Slater Type Basis sets for the molecules in the GW100 database. To this end, we present two new Slater Type orbital (STO) basis sets of triple- (TZ) and quadruple-$\zeta$ (QZ) quality whose polarization is adequate for correlated-electron methods and which contain extra diffuse functions to be able to correctly calculate electron affinities of molecules with a positive Lowest Unoccupied Molecular Orbital (LUMO). We demonstrate, that going from TZ to QZ quality consistently reduces the basis set error of our computed IPs and EAs and we conclude that a good estimate of these quantities at the CBS limit can be obtained by extrapolation. With MADs from 70 to 85 meV, our CBS limit extrapolated ionization potentials are in good agreement with results from FHI-AIMS, TURBOMOLE, VASP and WEST while they differ by more than 130 meV on average from nanoGW. With a MAD of 160 meV, our electron affinities are also in good agreement with the WEST code. Especially for systems with positive LUMOs, the agreement is excellent. With respect to other codes, the STO type basis sets generally underestimate EAs of small molecules with strongly bound LUMOs. With 62 meV for IPs and 93 meV for EAs, we find much better agreement to CBS limit extrapolated results from FHI-AIMS for a set of 250 medium to large organic molecules.