Coulomb-Sturmian basis for the nuclear many-body problem

TL;DR

This paper introduces Coulomb-Sturmian functions as a new basis for nuclear many-body calculations, offering better asymptotic properties than traditional harmonic-oscillator bases, demonstrated through calculations for 6Li.

Contribution

It establishes the theoretical foundation for using Coulomb-Sturmian functions in ab initio nuclear calculations, improving the description of wave function asymptotics.

Findings

Coulomb-Sturmian basis provides realistic exponential falloff.

Successful application to 6Li nucleus.

Analysis of center-of-mass separation and spurious states.

Abstract

Calculations in ab initio no-core configuration interaction (NCCI) approaches, such as the no-core shell model or no-core full configuration methods, 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 wave function. We establish the foundations for carrying out NCCI calculations with an alternative many-body basis built from Coulomb-Sturmian functions. These provide a complete, discrete set of functions with a realistic exponential falloff. We present illustrative NCCI calculations for 6Li with a Coulomb-Sturmian basis and investigate the center-of-mass separation and spurious excitations.