paper

Controlled bond expansion for DMRG ground state search at single-site costs

arXiv:2207.14712 · doi:10.1103/PhysRevLett.130.246402

Abstract

DMRG ground state search algorithms employing symmetries must be able to expand virtual bond spaces by adding or changing symmetry sectors if these lower the energy. Traditional single-site DMRG does not allow bond expansion; two-site DMRG does, but at much higher computational costs. We present a controlled bond expansion (CBE) algorithm that yields two-site accuracy and convergence per sweep, at single-site costs. Given a matrix product state defining a variational space, CBE identifies parts of the orthogonal space carrying significant weight in and expands bonds to include only these. CBE-DMRG uses no mixing parameters and is fully variational. Using CBE-DMRG, we show that the Kondo-Heisenberg model on a width 4 cylinder features two distinct phases differing in their Fermi surface volumes.

12 pages, 10 figures

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