The seniority quantum number in Tensor Network States

TL;DR

This paper uses tensor network methods to study the seniority quantum number in molecular systems, addressing limitations of seniority-zero approaches by allowing higher seniority levels to improve accuracy in describing molecular properties.

Contribution

It introduces a systematic approach to incorporate higher seniority numbers in tensor network states, enhancing the treatment of dynamical correlation in molecular systems.

Findings

Seniority levels influence the accuracy of molecular binding descriptions.

Higher seniority numbers improve the modeling of dispersion and dynamical correlation.

The method successfully describes the symmetry of benzene and binding in diatomic molecules.

Abstract

We employ tensor network methods for the study of the seniority quantum number - defined as the number of unpaired electrons in a many-body wave function - in molecular systems. Seniority-zero methods recently emerged as promising candidates to treat strong static correlations in molecular systems, but are prone to deficiencies related to dynamical correlation and dispersion. We systematically resolve these deficiencies by increasing the allowed seniority number using tensor network methods. In particular, we investigate the number of unpaired electrons needed to correctly describe the binding of the neon and nitrogen dimer and the $D_{6h}$ symmetry of benzene.