Quantum-mechanical Simulation of the IR Reflectance Spectrum of Mn 3 Al 2 Si 3 O 12 Spessartine
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Ferrari, A. and Demichelis, R. and Pascale, F. and Meyer, A. and Maschio, L. and Dovesi, R. 2015. Quantum-mechanical Simulation of the IR Reflectance Spectrum of Mn 3 Al 2 Si 3 O 12 Spessartine, in Simos, T. and Maroulis, G. (ed), Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2010 (ICCMSE-2010), Oct 3-8 2010, pp. 555-558. Kos, Greece.
AIP Conference Proceedings
International Conference of Computational Methods in Sciences and Engineering 2010
The reflectance spectrum of one member of the garnet family, Mn3Al2Si3O12 spessartine, was computed at the ab initio level with an all electron Gaussian type basis set and the B3LYP Hamiltonian. The static high frequency dielectric constant was obtained by applying the Coupled Perturbed Kohn Sham scheme as implemented in the CRYSTAL code; the Hessian matrix was evaluated numerically starting from the analytical gradients of the total energy with respect to the Cartesian coordinates of the atoms; the oscillator strengths were computed from well localized Wannier functions. An excellent agreement was obtained with the corresponding experimental spectrum, the exception being the very low frequency region.