xDMRG++

Introduction

The density matrix renormalization group (DMRG) is a variational method for one-dimensional quantum systems. In xDMRG++, many-body states are represented as matrix product states (MPS), and Hamiltonians as matrix product operators (MPO). The code is aimed at finite and infinite lattice calculations in one dimension, with an emphasis on finite-chain excited states and dynamics in the many-body localized regime.

The available algorithms are:

• xDMRG: Excited state DMRG. Targets interior eigenstates on finite chains.

• fDMRG: finite DMRG. Targets extremal eigenstates, most commonly the ground state, on finite chains.

• iDMRG: infinite DMRG. Targets ground states of infinite translationally invariant systems.

• iTEBD: Imaginary Time Evolving Block Decimation. Finds ground states of infinite translationally invariant systems by imaginary-time evolution.

• fLBIT: Finite l-BIT. Time evolution of finite systems in terms of local integrals of motion in the many-body localized regime.

The pages below focus on how to configure, build, and run the code. The documentation does not attempt to reproduce every implementation detail from the source tree, but it does point to the main configuration interfaces and to the parts of the code where new models and algorithms are introduced.

Contents

• Installation
  • Requirements
  • Dependencies
  • Quick start with CMake Presets
  • Automatic Dependency Installation
  • CMake Options
• Usage
  • Input Configuration File
  • Output Data File
  • Model Hamiltonians
• Settings
  • Input
  • Storage and Output
  • Model Hamiltonian
  • Algorithms
  • Algorithm Strategies
  • Algorithm Precision
  • Threading
  • Timer
  • Console