A constrained-path quantum Monte-Carlo approach for the nuclear shell model

Abstract

A new Quantum Monte-Carlo (QMC) approach is proposed to investigate low-lying states of nuclei within the shell model. The formalism relies on a variational symmetry-restored wave-function to guide the underlying Brownian motion. Sign/phase problems that usually plague QMC fermionic simulations are controlled by constraining stochastic paths through a fixed-node like approximation. Exploratory results in the sd and pf valence spaces with realistic effective interactions are presented. They prove the ability of the scheme to yield nearly exact yrast spectroscopies for both even-and odd-mass nuclei.

Constrained-path quantum Monte Carlo approach for non-yrast states within the shell model

“…Given that such calculations are not subject to explicit manifestations of sign or phase problems, they may be performed in very large configuration spaces to obtain variational estimates of nuclear properties [47]. This method has been used to study the shape coexistence in 56 Ni [48], the structure of neutron-rich exotic nuclei [49], for example, and has been recently applied within an ab initio context to no-core calculations for the beryllium isotopes [50].…”