Finite Temperature Density Matrix Renormalization using an enlarged Hilbert space

TL;DR

This paper extends the time-dependent DMRG method to finite temperature quantum spin chains, demonstrating its effectiveness and comparing it favorably with transfer-matrix DMRG for models like the frustrated J1-J2 chain.

Contribution

It introduces a generalized finite temperature DMRG approach using an enlarged Hilbert space and discusses practical implementation issues.

Findings

Both methods produce excellent results for finite temperature properties.

The generalized approach effectively handles frustrated J1-J2 models.

Practical issues like quantum numbers and finite size effects are addressed.

Abstract

We apply a generalization of the time-dependent DMRG to study finite temperature properties of several quantum spin chains, including the frustrated $J_1-J_2$ model. We discuss several practical issues with the method, including use of quantum numbers and finite size effects. We compare with transfer-matrix DMRG, finding that both methods produce excellent results.