Spin-Hamiltonian parameters and angular distortion for the trigonal Nd(3+) center in congruent LiNbO(3)

The 52x52 energy matrix related to the ground multiplet (4)I(9/2) and the first to third excited multiplets (4)I(11/2), (4)I(13/2) and (4)I(15/2) for 4f(3) ions in trigonal crystal field under an external magnetic field is established. By diagonalizing the energy matrix, the spin-Hamiltonian parameters (g factor g(parallel), g(perpendicular) and hyperfine structure constants (143)A(parallel), (143)A( perpendicular), (145)A(parallel), (145)A( perpendicular)) of the trigonal Nd(3+) center in congruent LiNbO(3) crystal are calculated. The calculated results are in reasonable agreement with the experimental values. From the calculations, the negative signs of hyperfine structure constants are suggested and the angular distortion of the trigonal Nd(3+) center in LiNbO(3), which is unable to be determined by EXAFS measurement, is obtained. The results are discussed.