The local structure of Tm2+ and Yb3+ cubic impurity centers in MeF2:Tm2+ and MeF2:Yb3+ (Me = Ca, Sr, Ba) fluoride crystals, as well as Yb3+ trigonal and tetragonal impurity centers in MeF2:Yb3+ crystals, was calculated within the shell model in the pair potential approximation.

Local Structure of Tm2+ and Yb3+ Impurity Centers in MeF2 (Me = Ca, Sr, Ba) Fluoride Crystals. A.D.Gorlov, V.A.Chernyshev, M.Y.Ugryumov, A.V.Abrosimov: Physics of the Solid State, 2005, 47[8], 1439-42