Block Density Matrix Renormalization Group with Effective Interactions

TL;DR

The paper introduces BDMRG-EI, a new computational scheme combining CORE and DMRG methods, enabling efficient and accurate calculations of ground and excited states in large quantum systems with complex connectivity.

Contribution

It develops a novel method that integrates DMRG with CORE to handle larger blocks efficiently, improving computational accuracy and cost-effectiveness.

Findings

Successfully applied to a 240-site 1D chain.

Effective in calculating low-lying excited states.

Demonstrates high efficiency and potential for large systems.

Abstract

Based on the contractor renormalization group (CORE) method and the density matrix renormalization group (DMRG) method, a new computational scheme, which is called the block density matrix renormalization group with effective interactions (BDMRG-EI), is proposed to deal with the numerical computation of quantum correlated systems. Different from the convential CORE method in the ways of calculating the blocks and the fragments, where the DMRG method instead of the exact diagonalization is employed in BDMRG-EI, DMRG-EI makes the calculations of larger blocks and fragments applicable. Integrating DMRG's advantage of high accuracy and CORE's advantage of low computational costs, BDMRG-EI can be widely used for the theoretical calculations of the ground state and low-lying excited states of large systems with simple or complicated connectivity. Test calculations on a 240 site one-dimensional chain and a double-layer polyacene oligomer containing 48 hexagons demonstrate the efficiency and potentiality of the method.