The electronic structures, densities of states, Fermi surfaces and elastic properties of AB3 (A =La, Y; B =Pb, In, Tl) compounds are studied under pressure using the full-potential linear augmented plane wave (FP-LAPW) method within the local density approximation for the exchange-correlation functional and including spin-orbit coupling. Fermi surface topology changes are found for all the isostructural AB3 compounds under compression (at V/V0 = 0.90 for LaPb3 (pressure = 8 GPa), at V/V0 = 0.98 for AIn3 (pressure = 1.5 GPa), at V/V0 = 0.80 for ATl3 (pressure in excess of 18 GPa)) apart from YPb3, although its electronic structure at zero pressure is very similar to that of LaPb3. For LaPb3 a softening of the C44 elastic constant under pressure (equivalent to 8 GPa) may be related to the appearance of a new hole pocket around the X point. From the calculated elastic properties and other mechanical properties, all the compounds investigated are found to be ductile in nature with elastic anisotropy. The states at the Fermi level (EF) are dominated by B p states with significant contributions from the A d states. For the La compounds, small hybridizations of the La f states also occur around EF.

The electronic structure, Fermi surface, and elastic properties of the isostructural and isoelectronic LaSn 3 and YSn 3 intermetallic compounds are studied under pressure within the framework of density functional theory including spin-orbit coupling. The LaSn 3 Fermi surface consists of two sheets, of which the second is very complex. Under pressure a third sheet appears around compression V /V 0 = 0.94, while a small topology change in the second sheet is seen at compression V /V 0 = 0.90. This may be in accordance with the anomalous behavior in the superconducting transition temperature observed in LaSn 3 , which has been suggested to reflect a Fermi surface topological transition, along with a nonmonotonic pressure dependence of the density of states at the Fermi level. The same behavior is not observed in YSn 3 , the Fermi surface of which already includes three sheets at ambient conditions, and the topology remains unchanged under pressure. The reason for the difference in behavior between LaSn 3 and YSn 3 is the role of spin-orbit coupling and the hybridization of La 4f states with the Sn p states in the vicinity of the Fermi level, which is well explained using the band structure calculation. The elastic constants and related mechanical properties are calculated at ambient as well as at elevated pressures. The elastic constants increase with pressure for both compounds and satisfy the conditions for mechanical stability under pressure.

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The scaling relationships between the adsorption energies of different reaction intermediates have a tremendous effect in the field of surface science, particularly in predicting new catalytic materials. In the last...

We investigate the electronic structure of FeTe 0.6 Se 0.4 employing high resolution photoemission spectroscopy and ab initio band structure calculations. Fe 2p core level and the valence band spectra exhibit signature of strong electron correlation in the electronic structure. The electronic states near the Fermi level reduces in intensity with the decrease in temperature in conformity with the insulating transport observed near 300 K. An insulator to metal transition around 150 K could be related to the spectral lineshape change in the vicinity of the Fermi level. The spectral features near Fermi level exhibit significant p orbital character due to the correlation induced Fe d spectral weight transfer. The experimental spectra reveal dominant temperature dependence of the spectral functions possessing large p-character. While the origin of the anomalous electronic properties in the normal phase could be revealed in the electronic structure of this material, these results emphasizes the importance of ligand states in the high temperature superconductors that is important to explore such materials for various applications. V C 2013 AIP Publishing LLC.