A TEST OF THE APPLICATION OF EXTENDED HUCKEL CALCULATIONS TO THE THCR2SI2 AND CAAL2SI2 STRUCTURE TYPES - THE CASE OF SRMN2P2 AND BAMN2P2

AMn2P2 (A = Sr, Ba) is an example of a composition that can assume a d ifferent structure type, depending on the identity of the cation. BaMn 2P2 crystallizes in the ThCr2Si2 structure type, whereas SrMn2P2 cryst allizes in the CaAl2Si2 structure type. These compounds have been char acterized by temperature-dependent magnetic susceptibility, neutron di ffraction, and resistivity. The results indicate that extended Huckel calculations cannot adequately account for the electronic or magnetic properties of these compounds. (C) Academic Press, Inc.