zhangwanzhou / sse-disordered Goto Github PK

The repository provides a minimal implementation for the stochastic series expansion algorithm -- a highly efficient Quantum Monte Carlo algorithm for the simulation of the Spin-1/2 XXZ model or hard-core boson model in thermal equilibrium. The detailed description of the algorithm can be found at https://arxiv.org/abs/cond-mat/0202316. The focus of the implementation is two-fold: first, I provide an efficient implementation without additional coding overhead in order to allow beginners to easily modify the Quantum Monte Carlo simulation for their purposes as fast as possible. Second, the implementation adds support for diagonal and off-diagonal disorder, i.e., it extents the algorithm explicitly discussed in the above publication to the case of non-translational invariant Hamiltonians. Therefore, no symmetries between possible vertex configurations exists. For all possible vertex configurations consult Fig. 8 in https://arxiv.org/abs/cond-mat/0202316. To my knowledge this is the only open source implementation that provides support for the general, non-translational invariant case. In this general case the directed loop equations have to be solved for each site in real space separately. Depending on the random field and random hopping at the site, bounces in the directed loop construction can be either avoided or the probability can be minimized by bouncing on the vertex configuration with the highest weight.

To run the Quantum Monte Carlo simulation specify the system parameters in the python script run_SSE.py and execute the script. The specific disorder distribution for the disorder average can be modified in the python script disorder_average.py.

Copyright © 2019 Tobias Pfeffer

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

A copy of the GNU General Public License is available in the file LICENSE.txt.