XDiag

High-performance Yxact Diagonalization Routines and Algorithms

A C++ library to perform efficient Exact Diagonalizations of quantum many body systems.

Features:

Basic algebra of operators in quantum many-body systems
Iterative linear algebra for computing eigendecompositions and time-evolutions (e.g. Lanczos algorithm)
Local spin, t-J, or fermionic models
Full support of generic space group symmetries
parallelization both with OpenMP and MPI
modern C++17 impementation simplifying usage
wrapped in a convenient Julia library: XDiag.jl

Installation:

Clone this repository first. Afterwards, the xdiag library can be compiled using the standard CMake instructions

cmake -S . -B build
cmake --build build
cmake --install build

Example Code:

#include <xdiag/all.hpp>

using namespace xdiag;

int main() try {

  int n_sites = 16;
  int nup = n_sites / 2;
  Spinhalf block(n_sites, nup);

  // Define the nearest-neighbor Heisenberg model
  OpSum ops;
  for (int i = 0; i < n_sites; ++i) {
    ops += Op("HB", "J", {i, (i + 1) % n_sites});
  }
  ops["J"] = 1.0;

  set_verbosity(2);                // set verbosity for monitoring progress
  double e0 = eigval0(ops, block); // compute ground state energy

  Log("Ground state energy: {:.12f}", e0);

} catch (Error e) {
  error_trace(e);
}

Documentation

The full documentation is available at awietek.github.io/xdiag.

About

author: Alexander Wietek license: Apache License 2.0

awietek / xdiag

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