Based on the complete energy matrix approach, the local structure and zero field splitting (ZFS) parameter for ZnSiF6 center dot 6H(2)O:Ni2+ (V2+) systems are theoretically studied for 3d(n) (n = 3, 8) ions in trigonal symmetry at different pressure. In this approach, the contributions from the admixture of d orbitals of the central ions with the p orbitals of the ligands are considered. In addition, the relationships between the ZFS parameter D and the pressure P as well as the local structure parameter theta are discussed. The effects of the average parameter zeta(1) and the different parameter zeta(2) on the ZFS parameter D are analyzed. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.