Computer Package for Microscopic Spin Hamiltonian Analysis of the 3d4and 3d5(spin S = 2) Ions at Orthorhombic and Tetragonal Symmetry Sites

Abstract A FORTRAN package based on the microscopic spin Hamiltonian expressions derived by computer algebra (ALTRAN) for the high spin ( S = 2) 3 d 4 and 3 d 6 ions with an orbital singlet ground state at orthorhombic (point groups: C 2 v , D 2 , D 2 h ) and tetragonal (point groups: C 4 v , D 4 , D 4 h , D 2 d ) symmetry sites is presented. The spin—orbit (λ) and the spin—spin ( ρ ) coupling contributions up to the fourth-order perturbation theory are taken into account within the 5 D approximation. The package enables efficient numerical calculations of the Zeeman electronic (Ze) parameters and the zero-field splitting (ZFS) parameters for the S = 2 3 d 4 and 3 d 6 ions. The following terms are included: λ and λ 2 for the Ze parameters, λ 2 , λ 3 λ 4 , ρ , ρ 2 and λ 2 ρ for the second-rank ZFS ones, and λ 4 , ρ 2 and λ 2 ρ for the fourth-rank ZFS ones. The program is applicable to all possible energy level schemes with a ground orbital singlet arising from the 5 D multiplet due to orthorhombic or tetragonal symmetry crystal fields. The input parameters are λ , ρ , the energy levels Δ j ( j = 1, 2, 3, 4) and the mixing coefficient s , which can be obtained from other spectroscopic data. The ZFS parameters output in the extended Stevens notation B k q and b k q , as well as the conventional notation ( D , E ; a , F , K ), is provided.