Longitudinal static optical properties of hydrogen chains: finite field extrapolations of matrix product state calculations

TL;DR

This paper presents high-accuracy finite field calculations of optical properties of hydrogen chains using matrix product states, enabling extrapolation to the thermodynamic limit and assessment of quantum chemical methods.

Contribution

It introduces a sweep algorithm for SU(2) x U(1) invariant MPS and applies it to compute optical properties of hydrogen chains, extending to the thermodynamic limit.

Findings

Accurate finite field results for hydrogen chains' polarizabilities.

Successful extrapolation of properties to the thermodynamic limit.

Assessment of quantum chemical methods' performance.

Abstract

We have implemented the sweep algorithm for the variational optimization of SU(2) x U(1) (spin and particle number) invariant matrix product states (MPS) for general spin and particle number invariant fermionic Hamiltonians. This class includes non-relativistic quantum chemical systems within the Born-Oppenheimer approximation. High-accuracy ab-initio finite field results of the longitudinal static polarizabilities and second hyperpolarizabilities of one-dimensional hydrogen chains are presented. This allows to assess the performance of other quantum chemical methods. For small basis sets, MPS calculations in the saturation regime of the optical response properties can be performed. These results are extrapolated to the thermodynamic limit.