An open-source program package for numerical diagonalization of quantum spin systems. The FORTRAN source programs are relatively simple and highly readable, and it can be applied to various quantum spin systems by modifying the main routine. Both the Lanczos and the inverse iteration methods are implemented for calculation of eigenvalues and eigenvectors, as well as correlation functions. Can be also used for diagonalization problems of general sparse matrices.
Fortran codes for computing the specified k-th eigenvalue and eigenvector for generalized symmetric definite eigenvalue problems. Sylvester’s law of inertia is employed as the fundamental principle in computations, and the sparse direct linear solver (MUMPS) is used in the main routine. By inputting Hamiltonian and its overlap matrices, user can compute electron’s energy and its wave function in the specified k-th energy level.
QDS (Quantum Dynamics Simulator) is a program for computing magnetization curves and spectra of electron-spin resonance (ESR) in molecular magnets. Input data of this program can be magnetic interactions, the shape of a molecule, etc. Calculation is carried out with the combination of exact diagonalization, the quantum master equation, and the Kubo formula. It can be chosen whether the dissipation exists or not in the calculations of dynamical magnetization curves.
An open-source program package for numerical diagonalization based on the Lanczos method, specialized for spin chains with unit spin magnitude, S=1. This package, which uses another open-source program package, TITPACK, calculates eigenenergies and eigenvectors of ground states and low-lying excited states of spin chains with finite length. By the subspace partitioning method, both memory and cpu-time requirements are considerably reduced.