RT info:eu-repo/semantics/article T1 Lattice distortions around a Tl(+) impurity in NaI:Tl(+) and CsI:Tl(+) scintillators: An ab initio study involving large active clusters A1 Aguado Rodríguez, Andrés A1 Ayuela Fernández, Andrés A1 López Rodríguez, José Manuel A1 Alonso Martín, Julio Alfonso K1 Física AB Ab initio perturbed ion cluster-in-the-lattice calculations of the impurity centers NaI:Tl(+) and CsI:Tl(+) arepresented. We study several active clusters of increasing complexity and show that the lattice relaxation aroundthe Tl1 impurity implies the concerted movement of several shells of neighbors. The results also reveal theimportance of considering a set of ions that can respond to the geometrical displacements of the inner shells byadapting self-consistently their wave functions. Comparison with other calculations involving comparativelysmall active clusters serves to assert the significance of our conclusions. Contact with experiment is made bycalculating absorption energies. These are in excellent agreement with the experimental data for the mostrealistic active clusters considered. PB The American Physical Society YR 1998 FD 1998 LK http://uvadoc.uva.es/handle/10324/2508 UL http://uvadoc.uva.es/handle/10324/2508 LA eng NO Physical Review B, v. 58, n. 18 (1998) p. 11964-11969 NO Producción Científica DS UVaDOC RD 18-abr-2024