Accession Number : AD0618223

Title :   EFFECTIVE POLARIZING FIELD IN IONIC CRYSTALS.

Descriptive Note : Semi-Annual technical rept. no. 1,

Corporate Author : NEW MEXICO STATE UNIV UNIVERSITY PARK RESEARCH CENTER

Personal Author(s) : Theimer,O. ; Paul,R.

Report Date : JUN 1965

Pagination or Media Count : 8

Abstract : The polarizing field E in ionic crystals is calculated from a 'rigid ion' model in which the spherical charge cloud of the valence electrons is displaced rigidly against the ionic core under the influence of an electrical field. It is shown that overlap between neighboring charge clouds affects the Lorentz field, (4pi/3)Pg, (P = microscopic polarization) in such a fashion that the Lorentz factor g becomes equal to 1 + delta even in crystals with tetrahedral symmetry where it is generally assumed equal to unity. The overlap correction delta is calculated on the assumption that the wave functions of the valence electrons may be approximated by Slater functions, i. e., hydrogen-like wave functions with effective, non-integral atomic numbers Z*, and quantum number n*. Using Slater's empirical values for Z* and n*, delta is found of the order 0.1 for crystals with large anions and small cations such as sodium bromide and lithium iodide. For most other crystals delta is found of the order 0.01. (Author)

Descriptors :   (*CRYSTALS, IONS), (*FIELD THEORY, CRYSTALS), POLARIZATION, ELECTRIC FIELDS, ATOMIC CHARGE, REFRACTIVE INDEX, VALENCE, QUANTUM THEORY, CRYSTAL LATTICES

Distribution Statement : APPROVED FOR PUBLIC RELEASE