The ground state properties of fluorite (CaF2) have been studied using CRYSTAL, an ab initio periodic Hartree-Fock program. Twenty-two and thirteen atomic orbitals (represented as contracted Gaussian-type functions) are used for the calcium and fluorine atoms, respectively. The binding energy (BE), the equilibrium lattice parameter (a), the elastic constants (Cij) and the central zone phonon frequencies nu (IR) and nu (Raman) have been evaluated, and a good agreement obtained with experiment (for instance the error is +2.0, +1.7, -0.5% for BE, a and C11, respectively). The calculated C44 elastic constant reduces from 48 to 44 GPa (experimental value: 37 GPa) when the fluorine atoms are allowed to displace under strain, indicating the importance of inner deformation for shear elasticity. Electron density maps, density of states and band structure plots are reported which confirm the fully ionic nature of fluorite.

Elastic constants and electronic structure of fluorine (CaF2): an ab initio Hartree-Fock study / M. Catti, A. Pavese, R. Dovesi, V. Saunders. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - 3:23(1991), pp. 004.4151-004.4164.

Elastic constants and electronic structure of fluorine (CaF2): an ab initio Hartree-Fock study

A. Pavese
Secondo
;
1991

Abstract

The ground state properties of fluorite (CaF2) have been studied using CRYSTAL, an ab initio periodic Hartree-Fock program. Twenty-two and thirteen atomic orbitals (represented as contracted Gaussian-type functions) are used for the calcium and fluorine atoms, respectively. The binding energy (BE), the equilibrium lattice parameter (a), the elastic constants (Cij) and the central zone phonon frequencies nu (IR) and nu (Raman) have been evaluated, and a good agreement obtained with experiment (for instance the error is +2.0, +1.7, -0.5% for BE, a and C11, respectively). The calculated C44 elastic constant reduces from 48 to 44 GPa (experimental value: 37 GPa) when the fluorine atoms are allowed to displace under strain, indicating the importance of inner deformation for shear elasticity. Electron density maps, density of states and band structure plots are reported which confirm the fully ionic nature of fluorite.
Settore GEO/06 - Mineralogia
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/180155
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