Search

Within the framework of an unified ab initio approach the crystal structure, the effect of hydrostatic pressure on the crystal structure, and the phonon spectra of crystals FeBO3 and GaBO3 were investigated. Also, an analysis of the displacement vectors has been obtained from the ab initio calculation, which made it possible to estimate the degree of the ion displacements in each vibrational mode. Calculations were carried out within the framework of MO LCAO approach and the density functional theory, by using PBE0 hybrid functional which takes into account both the local and nonlocal (in the Hartree--Fock formalism) exchange.The calculations were performed with CRYSTAL14 software designed to simulate periodic structures. The results of the performed calculations suggest new features of the title crystals under pressure and new vibrational properties. [ABSTRACT FROM AUTHOR]

In this paper we carried out the ab initio calculations of the impurity centers Y3Al5O12: R3+ (R= La-Lu) by investigation doped crystal structure and its elastic properties. The crystal structure of impurity centers was investigated and the elastic constants of the crystals RE3Al5O12 (RE = Y, La-Lu) were calculated. The effect of hydrostatic pressure on the elastic properties of RE3Al5O12 (RE = Y, La-Lu) was investigated also. Ab initio calculations were performed in periodic CRYSTAL code within the framework of the MO LCAO approach by using hybrid DFT functionals. The results obtained can be used to interpret experimental data and predict the new properties of YAG: R3+ laser materials. [ABSTRACT FROM AUTHOR]