The phase transition in alkaline-earth oxides: a comparison ofab initioHartree-Fock and density functional calculations

Abstract

Structural properties of the (NaCl-type) and (CsCl-type) phases of alkaline-earth oxides and their phase transition have been investigated with the periodic ab initio linear combination of atomic orbitals method implemented in the CRYSTAL program. The geometries have been optimized and the bulk modulus evaluated. The calculations have been done at the Hartree-Fock (HF) and density functional theory (DFT) levels. In this last case, the exchange-correlation potential correcting the electronic density uses either one local or three non-local models. The comparison of the different approaches allows us to identify a trend, in order to obtain results in better agreement with experiment.

High-pressure and temperature-induced structural, elastic, and thermodynamical properties of strontium chalcogenides

“…The value of relative volumes is shown in Table 2. It is also compared with various experimental [3][4][5] and other theoretical works [2,9]. Compressions in SrX at higher pressure indicate the mechanical stiffenening of lattice.…”

“…In view of the reported literature on technological important monochalcogenides as SrX (X = O, S, Se, and Te) [1][2][3][4][5][6][7][8][9][10][11][12], we notice that both the quantum calculations and the lattice model calculations predict the pressure-induced ground state properties and no efforts have been made to explore the temperature-dependent elastic, thermal, and thermodynamical properties of these chalcogenides. In view of these, we made systematic efforts to investigate (a) pressure-induced, and (b) temperature-induced properties.…”

“…The full-potential linear augmented plane-wave method (FP-LAPW) has been exercised to probe the ground state properties such as lattice parameter, bulk modulus, and its pressure derivative, elastic constant and structural stability of the compound SrS, SrSe, and SrTe, respectively [1][2][3][4][5][6][7][8][9][10][11][12].…”

“…Structural properties of the B1 and B2 phases of alkaline earth oxides and their phase transition have been investigated using ab initio linear muffin-tin-orbital (LMTO) method [9]. The phase transition of SrS from NaCl (B1) structure to CsCl (B2) structure is investigated by means of ab initio plane-wave pseudo potential density function theory [10].…”

Ab initio theory of planetary materials

“…It is expected that under extreme pressure the CsCltype ("B2") structure will become stable, but the best theoretical calculations [21][22][23][24][25] indicate that the pressure of such a transition is very high, $510 GPa. Table 2 gives a summary of the calculated properties (lattice parameter and volume, bulk modulus and its pressure derivatives, B1--B2 transition pressure (P tr ), dielectric constants, heat capacity, and entropy) of MgO in comparison with experiment, with overall good agreement.…”