Ab initio simulations of structural and radiative properties of laser crystals: example of LiNbO3:Nd

Abstract This contribution is devoted to discussing some aspects of the part ab initio quantum chemistry can play in the study of laser materials via the local embedded cluster approach. The evolution in the applications of the method is briefly surveyed. Special focus is put on its specific capabilities with respect to those of the semi-empirical Crystal Field Theory (CFT). Two of the most recent improvements of the method are presented. One concerns the theory of ab initio model potentials for representing the effect of the environment. The other relates to new developments in the accurate treatment of spin–orbit and electronic correlation, especially for rare-earths. Preliminary results concerning the application of these methods to the concrete case of the Nd 3+ ion in lithium niobate are reported. The need to account for steric and electrostatic relaxation is pointed out. The chapter ends on some prospective views regarding the possibilities of calculating transition probabilities and investigating the influence of defects on laser properties.