Response properties in phaseless auxiliary field quantum Monte Carlo

Ankit Mahajan; Jo S Kurian; Joonho Lee; David R Reichman; Sandeep Sharma

doi:10.1063/5.0171996

Response properties in phaseless auxiliary field quantum Monte Carlo

J Chem Phys. 2023 Nov 14;159(18):184101. doi: 10.1063/5.0171996.

Authors

Ankit Mahajan^{1

2}, Jo S Kurian², Joonho Lee^{1

3}, David R Reichman¹, Sandeep Sharma²

Affiliations

¹ Department of Chemistry, Columbia University, New York, New York 10027, USA.
² Department of Chemistry, University of Colorado, Boulder, Colorado 80302, USA.
³ Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.

PMID: 37937933
DOI: 10.1063/5.0171996

Abstract

We present a method for calculating first-order response properties in phaseless auxiliary field quantum Monte Carlo by applying automatic differentiation (AD). Biases and statistical efficiency of the resulting estimators are discussed. Our approach demonstrates that AD enables the calculation of reduced density matrices with the same computational cost scaling per sample as energy calculations, accompanied by a cost prefactor of less than four in our numerical calculations. We investigate the role of self-consistency and trial orbital choice in property calculations. We find that orbitals obtained using density functional theory perform well for the dipole moments of selected molecules compared to those optimized self-consistently.