New Generation of the Monte Carlo Shell Model for the K Computer Era

TL;DR

This paper introduces an advanced Monte Carlo Shell Model that leverages conjugate gradient and energy-variance extrapolation to enable large-scale nuclear structure calculations on supercomputers like the K computer.

Contribution

The paper presents a new generation of the Monte Carlo Shell Model incorporating novel numerical techniques for large-scale nuclear calculations.

Findings

Validated the method in ab initio calculations of light nuclei

Applied to neutron-rich Cr and Ni isotopes to study shell magicity

Demonstrated capability for large-scale shell-model calculations on supercomputers

Abstract

We present a newly enhanced version of the Monte Carlo Shell Model method by incorporating the conjugate gradient method and energy-variance extrapolation. This new method enables us to perform large-scale shell-model calculations that the direct diagonalization method cannot reach. This new generation framework of the MCSM provides us with a powerful tool to perform most-advanced large-scale shell-model calculations on current massively parallel computers such as the K computer. We discuss the validity of this method in ab initio calculations of light nuclei, and propose a new method to describe the intrinsic wave function in terms of the shell-model picture. We also apply this new MCSM to the study of neutron-rich Cr and Ni isotopes using the conventional shell-model calculations with an inert 40Ca core and discuss how the magicity of N = 28, 40, 50 remains or is broken.