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The local structures for V2+ in CsMgX3 (X = Cl, Br, I) are theoretically investigated from the perturbation formulas of the EPR parameters (zero-field splitting, g factors and the hyperfine structure constants) for a 3d(3) ion in trigonal symmetry based on the cluster approach. In these formulas, the contributions from the s-orbitals of the ligands, which were usually neglected in the previous treatments, are considered here. Based on the Studies, we find that the local angles beta (between the impurity-ligand bonding lengths and the C-3 axis) in the V2+ centers are larger than the angles beta(H) in the hosts, leading to the positive angular distortions Delta beta (= beta - beta(H)). The theoretical EPR parameters (particularly the results for CsMgI3) show improvement compared with those in absence of the ligand s-orbital contributions or the above angular distortions. (c) 2005 Elsevier B.V. All rights reserved.