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arXiv · 2401.00613

Extracting spectra in the shell model Monte Carlo method using imaginary-time correlation matrices

Y. Alhassid·M. Bonett-Matiz·C. N. Gilbreth·S. Vartak
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Abstract

Conventional diagonalization methods to calculate nuclear energy levels in the framework of the configuration-interaction (CI) shell model approach are prohibited in very large model spaces. The shell model Monte Carlo (SMMC) is a powerful technique for calculating thermal and ground-state observables of nuclei in very large model spaces, but it is challenging to extract nuclear spectra in this approach. We present a novel method to extract low-lying energy levels for given values of a set of good quantum numbers such as spin and parity. The method is based on imaginary-time one-body density correlation matrices that satisfy asymptotically a generalized eigenvalue problem. We validate the method in a light nucleus that allows comparison with exact diagonalization results of the CI shell model Hamiltonian. The method is applicable to other finite-size quantum many-body systems that can be described within a CI shell model approach.

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Y. Alhassid, M. Bonett-Matiz, C. N. Gilbreth, S. Vartak. 2023-12-31. Extracting spectra in the shell model Monte Carlo method using imaginary-time correlation matrices. https://arxiv.org/abs/2401.00613

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