Coupled perturbed HF/KS calculation of the dielectric constant of crystalline systems. the case of six members of the garnet family

Abstract

The dielectric constant ε of pyrope (Mg3Al 2(SiO4)3), grossular (Ca3Al 2(SiO4)3), andradite (Ca3Fe 2(SiO4)3), almandine (Fe3Al 2(SiO4)3), spessartine (Mn3Al 2(SiO4)3), and uvarovite (Ca3Cr 2(SiO4)3) garnets has been calculated by using for the first time the CPHF/KS computational scheme recently implemented in the CRYSTAL code. Garnets are large unit cell (80 atoms in the primitive cell) highly symmetric (Ia3d space group) compounds of relevant importance in geology and mineralogy. An all electron Gaussian type Basis Set has been adopted for all atoms. For the four compound containing transition metal atoms the unrestricted formulation of the HF or KS equations has been used. The Basis Set effect has been explored, as well as the influence of the adopted functional, that ranges from LDA to HF through GGA (PBE) and hybrids PBE0 and B3LYP. © 2012 American Institute of Physics.