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Abstract: The formation and site preference energies and volume changes of single and pair of defects of ternary alloying elements in γ-TiAl intermetallic compound were studied by the density functional theory. Slight tendency to clusterization of antisite defects has been found. This may lead to disorder in the system. The V and Cr atoms prefer to reside in the Ti sublattice. The formation energy for Cr–Cr, Cr–V and V–V nearest neighbour pairs are in the 1.3–2eV range. The Al antisite in Ti sublattice requires much less energy than the Ti antisite in Al sublattice. The amorphisation process of TiAl alloy was studied by means of high energy ball milling of Ti and Al elemental powders, which produces amorphous structure after 40h. The amorphous states were studied by the DFT calculations of many random atomic configurations and the results were compared with the NiAl compound. Possible explanation for the amorphisation of the TiAl compound is presented. [Copyright &y& Elsevier]

Abstract: Using the first-principles computations we have calculated phonon-dispersion relations and the phonon density of states for perovskite and post-perovskite phases of MgSiO3. From them using the quasiharmonic approximation we have estimated the free energies, bulk modulus and volume expansion coefficients of both structures at various pressures and temperatures. Our calculations indicate that the thermal expansivity of MgSiO3 changes very little across the phase transition. We have determined the P–T coexisting line of perovskite and post-perovskite phases. [Copyright &y& Elsevier]

Abstract: The structure, lattice dynamics and electronic band structure of Ni43.75Fe6.25Ti50 were obtained using ab initio calculations. The phonon dispersion relations and phonon density of states were calculated using the direct method. The stability of Ni50−x Fe x Ti50 structure for x=0.0, 6.25, 12.5, 25 has been investigated and shown that the orthorhombic structure is the most stable phase for x=25. [Copyright &y& Elsevier]

The formation and preference site energies and volume changes of single defects and pairs of defects of ternary alloying elements in NiAl intermetallic compound were studied by the density functional theory. Exceptionally, a small formation energy of Co defect in Ni sublattice was found. The Co, Cr, Fe atoms and vacancies prefer to reside in the Ni sublattice. The formation energy for Co–Co nearest neighbor pair is the smallest. The Ni antisite in Al sublattice requires less energy than the Al antisite in Ni sublattice. [Copyright &y& Elsevier]

Abstract: The phonon dispersion curves of the unconventional superconductor PuCoGa5 were studied by inelastic X-ray scattering at room temperature. The experimental data agree well with ab initio lattice dynamics calculations. An accurate theoretical description of the phonon spectrum is obtained only when a local Coulomb repulsion  eV among 5f electrons is taken into account. This implies partial localization of the 5f electrons in this compound. A comparison made with the phonon spectrum of UCoGa5 suggests that the latter compound is better described with a fully itinerant f electrons model. [Copyright &y& Elsevier]