An Introduction to the Density Matrix Renormalization Group Ansatz in Quantum Chemistry

TL;DR

This paper introduces the Density Matrix Renormalization Group (DMRG) method in quantum chemistry, highlighting its ability to solve complex multireference problems with large active spaces using a wavefunction perspective.

Contribution

It provides an expository introduction to the DMRG ansatz, emphasizing its application and advantages in ab-initio quantum chemistry.

Findings

Enables solving previously intractable multireference problems

Highlights the wavefunction perspective as more powerful

Demonstrates DMRG's effectiveness in large active spaces

Abstract

The Density Matrix Renormalisation Group (DMRG) is an electronic structure method that has recently been applied to ab-initio quantum chemistry. Even at this early stage, it has enabled the solution of many problems that would previously have been intractable with any other method, in particular, multireference problems with very large active spaces. Historically, the DMRG was not originally formulated from a wavefunction perspective, but rather in a Renormalisation Group (RG) language. However, it is now realised that a wavefunction view of the DMRG provides a more convenient, and in some cases more powerful, paradigm. Here we provide an expository introduction to the DMRG ansatz in the context of quantum chemistry.