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Projector Quantum Monte Carlo Method for Nonlinear Wave Functions

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Schwarz, LR 
Booth, GH 

Abstract

We reformulate the projected imaginary-time evolution of the full configuration interaction quantum Monte Carlo method in terms of a Lagrangian minimization. This naturally leads to the admission of polynomial complex wave function parametrizations, circumventing the exponential scaling of the approach. While previously these functions have traditionally inhabited the domain of variational Monte Carlo approaches, we consider recent developments for the identification of deep-learning neural networks to optimize this Lagrangian, which can be written as a modification of the propagator for the wave function dynamics. We demonstrate this approach with a form of tensor network state, and use it to find solutions to the strongly correlated Hubbard model, as well as its application to a fully periodic ab initio graphene sheet. The number of variables which can be simultaneously optimized greatly exceeds alternative formulations of variational Monte Carlo methods, allowing for systematic improvability of the wave function flexibility towards exactness for a number of different forms, while blurring the line between traditional variational and projector quantum Monte Carlo approaches.

Description

Keywords

0105 Mathematical Physics

Journal Title

Physical Review Letters

Conference Name

Journal ISSN

0031-9007
1079-7114

Volume Title

118

Publisher

American Physical Society
Sponsorship
Engineering and Physical Sciences Research Council (EP/J003867/1)
G. H. B. gratefully acknowledges funding from the Royal Society via a University Research Fellowship, as well as support from the Air Force Office of Scientific Research via Grant No. FA9550-16-1-0256. A. A. acknowledges support from the EPSRC, Grant No. EP/J003867/1. L. R. S. is supported by an EPSRC studentship.