Density matrix renormalization group algorithms with a single center site

TL;DR

This paper introduces a correction to the density matrix in DMRG algorithms that enables using a single center site, reducing computation time and preventing metastability issues, demonstrated on the Heisenberg S=1 chain.

Contribution

A novel correction to the density matrix allows DMRG calculations with a single center site, improving efficiency and stability over traditional methods.

Findings

Reduces computation time by a factor of 2 to 4

Eliminates metastable states in DMRG calculations

Successfully tested on the Heisenberg S=1 chain

Abstract

We develop a correction to the density matrix used in density matrix renormalization group calculations to take into account the incompleteness of the environment block. The correction allows successful calculations using only a single site in the center of the system, rather than the standard two sites, improving typical computation times by a factor of two to four. In addition, in many cases where ordinary DMRG can get stuck in metastable configurations, the correction eliminates the sticking. We test the new method on the Heisenberg S=1 chain.