Ab Initio Calculations of Even Oxygen Isotopes with Chiral Two- Plus Three-Nucleon Interactions

TL;DR

This paper introduces a multi-reference IM-SRG method for open-shell nuclei and demonstrates its effectiveness by accurately predicting energies of even oxygen isotopes using chiral NN and 3N interactions, validated against other many-body methods.

Contribution

It develops the first multi-reference IM-SRG approach for open-shell nuclei and applies it to oxygen isotopes, showing high accuracy and establishing it as a powerful ab initio tool.

Findings

Accurately reproduces experimental ground-state energies of oxygen isotopes.

Validates results with Importance-Truncated No-Core Shell Model and Coupled Cluster methods.

Demonstrates the predictive power of chiral two- and three-nucleon interactions.

Abstract

We formulate the In-Medium Similarity Renormalization Group (IM-SRG) for open-shell nuclei using a multi-reference formalism based on a generalized Wick theorem introduced in quantum chemistry. The resulting multi-reference IM-SRG (MR-IM-SRG) is used to perform the first ab initio study of even oxygen isotopes with chiral NN and 3N Hamiltonians, from the proton to the neutron drip lines. We obtain an excellent reproduction of experimental ground-state energies with quantified uncertainties, which is validated by results from the Importance-Truncated No-Core Shell Model and the Coupled Cluster method. The agreement between conceptually different many-body approaches and experiment highlights the predictive power of current chiral two- and three-nucleon interactions, and establishes the MR-IM-SRG as a promising new tool for ab initio calculations of medium-mass nuclei far from shell closures.