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QS3 for ED

This is a program package based on the (thick-restart) Lanczos method for analyzing a spin-1/2 XXZ-type quantum spin models on spatially uniform lattices near the fully polarized states. All of calculations including eigenvalue problems, expectation values for one/two-body spin operators, static/dynamical spin structure factors with QS3 is performed in the symmetry-adapted bases specified by the number N↓ of down spin and the wave-number k associated with the translational symmetry and without using the bit representation for specifying the spin configuration. Since this treatment, QS3 supports large-scale quantum systems containing more than 1000 sites with dilute N↓.

arXiv

https://arxiv.org/abs/2107.00872

Licence

MIT License

External routines/libraries

BLAS, LAPACK

Nature of problems

Physical properties (such as the total energy, the magnetic moment, the two-point spin correlation function, the dynamical structure factor)

Solution method

Application software based on the full diagonalization method?, and the exact diagonalization using the Lanczos and thick-restart Lanczos methods for quantum spin S = 1/2 models such as the XXZ model.

Restrictions

Spin S = 1/2 systems with the U(1) and translational symmetries.

Requirements

This package, containing the Fortran source codes, samples, and manual, is available. For the building, Fortran compiler with BLAS/LAPACK library is prerequisite.

Compile

For those who have their own Git accounts, simply clone the repository on their local computers:

$ git clone https://github.com/QS-Cube/ED.git

Otherwise, go to the web page and click the "Code" button and "Download ZIP" to get "ED-main.zip". The zip file is unpacked as

$ unzip ED-main.zip
$ cd ED-main

A simple Makefile is provided to build the executable files "QS3.exe" for systems preserving the translational symmetry and "QS3_only_u1.exe" for systems without the translational symmetry. The following procedures after the cloning or downloading will give the executable file and execute sample programs

$ cd script
$ ./make.sh

After executing samples, all results are stored in output directories.

Developers

Hiroshi Ueda and Tokuro Shimokawa