STRUCTURAL AND ELECTRONIC-PROPERTIES OF PYROPE GARNET (MG3AL2SI3O12) - AN AB-INITIO STUDY

The structural and electronic properties of the pyrope garnet have bee n investigated with the periodic ab initio quantum mechanical program CRYSTAL. An all-electron extended basis set of gaussian-type functions has been used. The geometrical parameters of the unit cell, which con tains 80 atoms, have been fully optimized. The calculated static geome try agrees with experiment. The bulk modulus and the enthalpy of forma tion from atoms (binding energy) and simple oxides (MgO, Al2O3, SiO2-q uartz) are also evaluated and turn out to be in good agreement with ex perimental results. Densities of states, charge-density maps and Mulli ken population data are used for discussing the electronic structure a nd nature of the different bonds of the system.