Simulation of optical and magnetic properties of neodymium (4f3) in the solid state:: extreme sensitivity to the wave vector's composition

The optical absorption spectra of neodymium at 4 K are reproduced with a very good agreement between calculation and experiment (15 < rms < 20 cm(-1)). The wavefunctions which are obtained as a result of the energy calculation can be used to compute other physical properties. Among them we consider the paramagnetic susceptibility and the electron paramagnetic resonance. We report the results of these calculations concerning six compounds (Nd2O2S, A-Nd2O3, NdOCl, NdOF, Nd3+:LaCl3 and NdF3) for which the optical absorption spectra were thoroughly interpreted. We notice that these properties, depending on the point symmetry of the neodymium, are very sensitive to the values of the coefficients of the kets in the wavefunctions. These wavefunctions are extremely dependent on the crystal field parameters (cfps). A regard on the magnetic properties is very useful to determine if a set of crystal field parameters which fits the overall Stark levels is also convenient for the ground state (I-4(9/2)) A comparison is also made between cfps determined from atomic positions in the structure (Simple Overlap Model) and phenomenological cfps. We also consider the effect of the spin-correlated crystal field (SCCF) through the action of its radial contribution represented by the c(k) parameters (k = 2,4,6). (C) 2001 Elsevier Science B.V. All rights reserved.