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
(Before running make.sh, open this file and select the compiler (ARG1=gfortran/ifort) and linear algebra library (ARG2=lapack/mkl).)
After executing samples, all results are stored in output directories.
If you have any problems compiling or installing QS3, or if you have any requests for future additional functions in QS3, please comment in the "Issues" tag of this repository, or contact the developers of QS3:
Hiroshi Ueda: ueda.hiroshi.qiqb@osaka-u.ac.jp
Tokuro Shimokawa: tokuro.shimokawa@oist.jp
We will reply to your comments after fixing the issues you found.
Hiroshi Ueda and Tokuro Shimokawa