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↓.
https://arxiv.org/abs/2107.00872
MIT License
BLAS, LAPACK
Physical properties (such as the total energy, the magnetic moment, the two-point spin correlation function, the dynamical structure factor)
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.
Spin S = 1/2 systems with the U(1) and translational symmetries.
This package, containing the Fortran source codes, samples, and manual, is available. For the building, Fortran compiler with BLAS/LAPACK library is prerequisite.
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.
Hiroshi Ueda and Tokuro Shimokawa