A theoretical method for investigating the inter-relation between the electronic and the molecular structures of a d(5) ion in a tetragonal ligand-field has been established on the basis of a 252 x 252 complete energy matrix. Using this method, the local structure parameters of the Fe3+-V-M system in AMF(3):Fe3+ crystals are determined by the experimental EPR spectra at T = 300 K. It is shown that, the local lattice structure around an octahedral Fe3+ center has a compression distortion along the crystalline axis in AMF(3):Fe3+ crystal. From our analysis, we also conclude that Delta R vs. 10(4)b(2)(0) is approximately linear for the Fe3+-V-M system in AMF(3):Fe3+ crystals. (c) 2006 Elsevier B.V. All rights reserved.