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A realistic interaction potential model approach by including temperature effects is developed to study phase transition, elastic properties and thermo-physical properties at very high pressures and temperatures. This approach is effectively able to explain the inter-atomic interaction involved at high temperature and high pressure as it includes the three-body interactions. Earlier works overlooked the three-body interactions at high temperature and pressures. Moreover, the phase-transition pressures of MgO crystal at high temperatures including the three-body interaction are computed for the first time. Elastic behavior, anisotropic factor and Debye temperature of MgO at high pressures and temperatures are also reported. [ABSTRACT FROM AUTHOR]

In present study we have investigated the high pressure phase transition, associated volume collapse, elastic and thermo-physical properties of praseodymium chalcogenides (PrX; X: S, Se, Te), using the three body interaction potential (TBIP) approach. These interactions arise due to the electron shell deformation of the overlapping ions in the crystals. The present TBIP model consists of long range Coulombic, three body interaction and the short range overlap repulsive forces operative up to next nearest neighbor ions. The praseodymium chalcogenides belong to the wide class of binary rare-earth monochalcogenides, which crystallize into NaCl structure under ambient conditions and undergo NaCl to CsCl phase transition under high pressure. The values of phase transition pressure, associated volume collapse, bulk modulus and its pressure derivative estimated by us are found to be well suited with experimental values. In view of its overall success, it can be regarded as an adequate and appropriate model suitable for high pressure studies. [ABSTRACT FROM AUTHOR]

A theoretical analysis of pressure induced phase transition of actinide monoarsenides having NaC1-type (B1) structure using realistic three body interaction potential model (RTBIPM) for Np, Pu, Th and U is presented. Present RTBIPM model parametrically includes different parameters separately for different phases which other theoretical workers ignore it. The phase transition pressures and elastic behavior of these actinide monoarsenides are found closer to the experimental results. A static simulation technique including three body interaction effects has been used to calculate the equation of state, pressure derivatives of elastic constants and their stability criterion. The important finding of the present study is the effect of high pressure on the three-body interaction effect at the structural phase transition pressure. Further, by using different parameters separately in the RTBIPM for different phases makes it realistic approach for high pressure studies. [ABSTRACT FROM AUTHOR]

In the present paper, monopnictides of Ce and La, which crystallize in B1 structure, have been studied using effective interaction potential (EIP) approach. The phase transition pressure and volume collapses for CeSb and LaSb predicted from this approach are found to be close to experimental data. [ABSTRACT FROM AUTHOR]

The high pressure phase transition and elastic behavior of rare earth monoselenides (CeSe, EuSe and LaSe) which crystallize in a NaCl-structure have been investigated using the three body interaction potential (TBIP) approach. These interactions arise due to the electronshell deformation of the overlapping ions in crystals. The TBP model consists of a long range Coulomb, three body interactions and the short range overlap repulsive forces operative up to the second neighboring ions. The authors of this paper estimated the values of the phase transition pressure and the associated volume collapse to be closer than other calculations. Thus, the TBIP approach also promises to predict the phase transition pressure and pressure variations of elastic constants of lanthanide compounds. [ABSTRACT FROM AUTHOR]