G. Vaitheeswaran

Effect of van der Waals interactions on the structural and elastic properties of black phosphorus

The structural and elastic properties of orthorhombic black phosphorus have been investigated using first-principles calculations based on density functional theory. The structural parameters have been calculated using the local density approximation (LDA), the generalized gradient approximation (GGA), and with several dispersion corrections to include van der Waals interactions. It is found that the dispersion corrections improve the lattice parameters over LDA and GGA in comparison with experimental results. The calculations reproduce well the experimental trends under pressure and show that van der Waals interactions are most important for the crystallographic b axis in the sense that they have the largest effect on the bonding between the phosphorus layers. The elastic constants are calculated and are found to be in good agreement with experimental values. The calculated C22 elastic constant is significantly larger than the C11 and C33 parameters, implying that black phosphorus is stiffer against strain along the a axis than along the b and c axes. From the calculated elastic constants, the mechanical properties, such as bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio are obtained. The calculated Raman active optical phonon frequencies and their pressure variations are in excellent agreement with available experimental results.

First-principles study of elastic properties of CeO2, ThO2 and PoO2

Using first-principles density functional calculations, the structural and elastic properties of fluorite type oxides CeO2, ThO2 and PoO2 were studied by means of the full-potential linear muffin-tin orbital method. Calculations were performed within the local density approximation (LDA) as well as generalized gradient approximation (GGA) to the exchange correlation potential. The calculated equilibrium lattice constants and bulk moduli are in good agreement with the experimental results, as are the computed elastic constants for CeO2 and ThO2. For PoO2 this is the first quantitative theoretical prediction of the ground state properties, and it still awaits experimental confirmation. The calculations find PoO2 to be a semiconductor with an indirect band gap and elastic constants similar in magnitude to those of CeO2 and ThO2.

Pseudo-half-metallicity in the double perovskite Sr2CrReO6 from density-functional calculations

The electronic structure of the spintronic material Sr2CrReO6 is studied by means of full-potential linear muffin-tin orbital method. Scalar relativistic calculations predict Sr2CrReO6 to be half-metallic with a magnetic moment of 1μB. When spin–orbit coupling is included, the half-metallic gap closes into a pseudo-gap, and an unquenched rhenium orbital moment appears, resulting in a significant increase of the total magnetic moment to 1.28μB. This moment is significantly larger than the experimental moment of 0.9μB. A possible explanation of this discrepancy is that the anti-site disorder in Sr2CrReO6 is significantly larger than hitherto assumed.The electronic structure of the spintronic material Sr

Elastic properties of MgCNi3 - a superconducting perovskite

_2

Phase Stability and Thermoelectric Properties of the Mineral FeS2: An Ab Initio Study

CrReO

Thermoelectric properties of chalcopyrite type CuGaTe2 and chalcostibite CuSbS2

_6

Electronic structure of samarium monopnictides and monochalcogenides

is studied by means of full-potential linear muffin-tin orbital method. Scalar relativistic calculations predict Sr

Magnetic moments of W 5d in Ca2CrWO6 and Sr2CrWO6 double perovskites

_2

Electronic structure, transport, and phonons of SrAgChF (Ch = S,Se,Te): Bulk superlattice thermoelectrics

CrReO

Electronic structure of the ferromagnetic double-perovskites Sr2CrReO6, Sr2CrWO6, and Ba2FeReO6

_6