Efficient implementation of the superposition of atomic potentials initial guess for electronic structure calculations in Gaussian basis sets

Susi Lehtola; Lucas Visscher; Eberhard Engel

doi:10.1063/5.0004046

Efficient implementation of the superposition of atomic potentials initial guess for electronic structure calculations in Gaussian basis sets

J Chem Phys. 2020 Apr 14;152(14):144105. doi: 10.1063/5.0004046.

Authors

Susi Lehtola¹, Lucas Visscher², Eberhard Engel³

Affiliations

¹ Department of Chemistry, University of Helsinki, P.O. Box 55 (A. I. Virtasen aukio 1), FI-00014 Helsinki, Finland.
² Division of Theoretical Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
³ Center for Scientific Computing, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main, Germany.

PMID: 32295364
DOI: 10.1063/5.0004046

Abstract

The superposition of atomic potentials (SAP) approach has recently been shown to be a simple and efficient way to initialize electronic structure calculations [S. Lehtola, J. Chem. Theory Comput. 15, 1593-1604 (2019)]. Here, we study the differences between effective potentials from fully numerical density functional and optimized effective potential calculations for fixed configurations. We find that the differences are small, overall, and choose exchange-only potentials at the local density approximation level of theory computed on top of Hartree-Fock densities as a good compromise. The differences between potentials arising from different atomic configurations are also found to be small at this level of theory. Furthermore, we discuss the efficient Gaussian-basis implementation of SAP via error function fits to fully numerical atomic radial potentials. The guess obtained from the fitted potentials can be easily implemented in any Gaussian-basis quantum chemistry code in terms of two-electron integrals. Fits covering the whole periodic table from H to Og are reported for non-relativistic as well as fully relativistic four-component calculations that have been carried out with fully numerical approaches.