Structural and electronic properties of pyrope garnet (Mg3Al2Si3O12): An ab initio study

The structural and electronic properties of the pyrope garnet have been 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 contains 80 atoms, have been fully optimized. The calculated static geometry agrees with experiment. The bulk modulus and the enthalpy of formation from atoms (binding energy) and simple oxides (MgO, Al2O3, SiO2-quartz) are also evaluated and turn out to be in good agreement with experimental results. Densities of states, charge-density maps and Mulliken population data are used for discussing the electronic structure and nature of the different bonds of the system.