INVESTIGATION OF MOSSBAUER PARAMETERS FOR A SET OF IODINE COMPOUNDS USING GRADIENT-CORRECTED DENSITY-FUNCTIONAL THEORY

In the present work we show the first application of density functiona l theory (DFT) with gradient-corrected exchange-correction functionals within the linear combination of Gaussian-type orbitals (LCGTO) forma lism to the calculation of isomer shifts and quadrupole couplings for a large and varied set of iodine compounds: I-2, ICI, IBr, ICN, HI, KI , CH3I, CH2I2, CHI3, CI4, SiI4, GeI4, and SnI4. The results are compar ed with experimental data from Mossbauer spectroscopy. The overall agr eement with experiment is most satisfactory, with the exception of the highly dipolar systems ICl, IBr, and ICN. For these systems it is bel ieved that the free molecule assumption of the calculations is not an entirely valid model of the crystalline environment of the experiments . (C) 1997 John Wiley & Sons, Inc.