Charge-transfer excited states: Seeking a balanced and efficient wave function ansatz in variational Monte Carlo

N S Blunt; Eric Neuscamman

doi:10.1063/1.4998197

Charge-transfer excited states: Seeking a balanced and efficient wave function ansatz in variational Monte Carlo

J Chem Phys. 2017 Nov 21;147(19):194101. doi: 10.1063/1.4998197.

Authors

N S Blunt¹, Eric Neuscamman¹

Affiliation

¹ Department of Chemistry, University of California, Berkeley, California 94720, USA.

PMID: 29166112
DOI: 10.1063/1.4998197

Abstract

We present a simple and efficient wave function ansatz for the treatment of excited charge-transfer states in real-space quantum Monte Carlo methods. Using the recently introduced variation-after-response method [E. Neuscamman, J. Chem. Phys. 145, 081103 (2016)], this ansatz allows a crucial orbital optimization step to be performed beyond a configuration interaction singles expansion, while only requiring calculation of two Slater determinant objects. We demonstrate this ansatz for the illustrative example of the stretched LiF molecule, for a range of excited states of formaldehyde, and finally for the more challenging ethylene-tetrafluoroethylene molecule.