Spin-adapted Matrix Product States and Operators

TL;DR

This paper introduces a method to incorporate non-abelian spin symmetry into matrix product states and operators, enhancing the efficiency of quantum chemical calculations by leveraging the Wigner--Eckart theorem.

Contribution

It presents a novel approach to exploit spin symmetry in MPSs and MPOs using the Wigner--Eckart theorem, improving computational methods in quantum chemistry.

Findings

Enhanced efficiency in spin-adapted quantum chemical calculations

Implementation of non-abelian spin symmetry in MPS/MPO frameworks

Demonstration of the approach with the quantum chemical Hamiltonian

Abstract

Matrix product states (MPSs) and matrix product operators (MPOs) allow an alternative formulation of the density matrix renormalization group algorithm introduced by White. Here, we describe how non-abelian spin symmetry can be exploited in MPSs and MPOs by virtue of the Wigner--Eckart theorem at the example of the spin-adapted quantum chemical Hamiltonian operator.