# The seniority quantum number in Tensor Network States

### Submission summary

 As Contributors: Klaas Gunst Preprint link: scipost_202008_00004v1 Code repository: https://github.com/klgunst/T3NS Date submitted: 2020-08-04 15:20 Submitted by: Gunst, Klaas Submitted to: SciPost Chemistry Academic field: Chemistry Specialties: Quantum Physics Theoretical and Computational Chemistry Approaches: Theoretical, Computational

### 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.

###### Current status:
Editor-in-charge assigned