The no-core shell model with general radial bases

TL;DR

This paper develops a new approach for no-core shell model calculations using general radial basis functions, like Coulomb-Sturmian functions, to better describe nuclear wavefunctions' asymptotic behavior.

Contribution

It introduces a framework for NCSM calculations with non-harmonic radial bases, addressing limitations of traditional harmonic oscillator bases.

Findings

Establishes theoretical foundations for using general radial bases in NCSM.

Discusses considerations for implementing Coulomb-Sturmian basis.

Highlights potential improvements in describing nuclear asymptotics.

Abstract

Calculations in the ab initio no-core shell model (NCSM) have conventionally been carried out using the harmonic-oscillator many-body basis. However, the rapid falloff (Gaussian asymptotics) of the oscillator functions at large radius makes them poorly suited for the description of the asymptotic properties of the nuclear wavefunction. We establish the foundations for carrying out no-core configuration interaction (NCCI) calculations using a basis built from general radial functions and discuss some of the considerations which enter into using such a basis. In particular, we consider the Coulomb-Sturmian basis, which provides a complete set of functions with a realistic (exponential) radial falloff.