SPINSGA: A program package for the evaluation of properties of spin-12 Heisenberg systems using the symmetric group approach Original Research Article

A set of programs for computing properties of spin-12 Heisenberg lattices is presented. The programs make full use of the spin symmetry inherent in these systems by operating in the fully S,M-adapted spin basis. This considerably reduces dimensions of the Hamiltonian matrices to be diagonalized. Properties, such as energies and correlation functions, are calculated after determination of the corresponding wavefunctions. Since the calculations are independent of lattice symmetries, the programs are most useful for treating unsymmetrical systems like hole doped lattices. Recent calculations were performed for systems containing up to 30 spins for both S = 0 and S = 1, the latter cases involving Hamiltonian matrix dimensions of ≈ 2.56 × 107.