Title: Computation of ground-state properties in molecular systems: back-propagation with auxiliary-field quantum Monte Carlo,
Abstract: We address the computation of ground-state properties of chemical systems and
realistic materials within the auxiliary-field quantum Monte Carlo method. The
phase constraint to control the fermion phase problem requires the random walks
in Slater determinant space to be open-ended with branching. This in turn makes
it necessary to use back-propagation (BP) to compute averages and correlation
functions of operators that do not commute with the Hamiltonian. Several BP
schemes are investigated and their optimization with respect to the phaseless
constraint is considered. We propose a modified BP method for the computation
of observables in electronic systems, discuss its numerical stability and
computational complexity, and assess its performance by computing ground-state
properties for several substances, including constituents of the primordial
terrestrial atmosphere and small organic molecules.