FIRST PRINCIPLES MODEL-CALCULATIONS OF IN-BR- BONDING()

In order to elucidate the unusual chemical bonding of the In+-Br- comb ination, the potential energy surfaces of the model complexes InBr87-, In7Br8- and InBr1211- have been studied by means of ab initio all-ele ctron calculations at the STO-3G, STO-3G, and MP2/STO-3G* levels of t heory. In all cases, the highest-symmetry geometrical configurations a re local maxima of the energy surfaces. Moreover, the crystal potentia ls around In+ are very soft, allowing small spontaneous distortions as a result of a second-order Jahn-Teller instability. The limits of the oretical accuracy obtainable at the present time are critically evalua ted.