The static crystal energy of calcite and its structure configuration as functions of pressure were determined by ab initio all-electron periodic Hartree-Fock calculations (CRYSTAL code). Ca, O and C atoms were represented by 22, 18 and 14 atomic orbitals, respectively, in form of contracted Gaussian-type functions. Comparison between theoretical and experimental data was performed for binding energy, equilibrium unit-cell and bond lengths, bulk modulus and C33 and C11 + C12 elastic constants, and vibrational frequency of the symmetrical C-O stretching mode. The agreement is generally satisfactory. A larger compressibility is observed for structural parameters of calcite than for those of magnesite coming from a similar calculation. The Ca-O and C-O chemical bonding was characterized by electron density maps and by Mulliken atomic charges; these are discussed and compared to values determined by empirical fitting of Born-type interatomic potentials.
|Titolo:||Quantum-mechanical Hartree-Fock study of calcite at variable pressure, and comparison with magnesite|
PAVESE, ALESSANDRO (Secondo)
|Settore Scientifico Disciplinare:||Settore GEO/06 - Mineralogia|
|Data di pubblicazione:||1993|
|Digital Object Identifier (DOI):||10.1007/BF00207203|
|Appare nelle tipologie:||01 - Articolo su periodico|