Comment on "Ab Initio study of 40-Ca with an importance-truncated no-core shell model"

TL;DR

This paper critiques a recent importance-truncation scheme for the no-core shell model applied to 40-Ca, arguing that the claimed convergence is not supported by the presented results and contradicts many-body theory expectations.

Contribution

It provides a critical analysis of the previous work, highlighting discrepancies and questioning the validity of the claimed convergence in the importance-truncation approach.

Findings

The critique questions the convergence claims of the original study.

Coupled-cluster calculations suggest significant missing correlation energy.

The paper emphasizes the need for careful validation of truncation schemes.

Abstract

In a recent Letter [Phys. Rev. Lett. 99, 092501 (2007)], Roth and Navratil present an importance-truncation scheme for the no-core shell model. The authors claim that their truncation scheme leads to converged results for the ground state of 40-Ca. We believe that this conclusion cannot be drawn from the results presented in the Letter. Furthermore, the claimed convergence is at variance with expectations of many-body theory. In particular, coupled-cluster calculations indicate that a significant fraction of the correlation energy is missing.