T. Nautiyal

Optical properties of A1N

Abstract We have performed calculations of the anisotropic frequency dependent dielectric function of AlN, using the linear muffin-tin orbital method within the atomic sphere approximation (LMTO-ASA). Our calculations show that the anisotropy is very small. The effect of introducing empty spheres is to decrease the energy gap by about 20% and to make the dielectric function slightly anisotropic at higher energies. Comparisons with experiments must await experimental results.

Band structure and optical properties of graphite

Abstract We report the first ever calculation of the frequency dependent anisotropic dielectric function of graphite. We have used the LMTO-ASA method including the combined correction terms. On comparison with the experimental data, we find good agreement as far as the anisotropy is concerned. The individual ϵ ⊥ ( ω ) and epsi ; | ( ω ) are also in reasonable agreement with the data.

Fermi surface of the noble metals

We report calculations of extremal areas of four Fermi surface (FS) orbits of the noble metals using the linear muffin tin orbital method in the atomic sphere approximation. Our calculations indicate that thel = 3 potential parameters and increase in the number of k-points in the Brillouin zone (BZ) summation from 240 to 916 have no significant effect on the FS. All calculations were performed self-consistently including up tol = 2 potential parameters and with 240 k points in the BZ summation. Calculations were performed with the exchange, correlation potentials (XCP) of Barth-Hedin, Barth-Hedin modified by Janak, SlaterXα, and the Vosko-Wilk-Nussair. Results compared with other theoretical calculations indicate that none of the above XC potentials give an accurate representation of the FS for all the noble metals. We feel that the inclusion of the non-locality of XCP may give a better account of the FS geometry.

Electronic properties and Fermi surface of Ni3Pt

Abstract We present calculations of the electronic properties of ordered Ni3Pt using the linear-muffin-tin-orbital method. Calculations are performed for the paramagnetic and ferromagnetic phases. Our total-energy calculations show that the ferromagnetic state has a lower energy. Hence the ferromagnetic phase is studied in detail. The calculations are done at a theoretical equilibrium lattice constant. The results for density of states, bulk modulus and magnetic moment at the equilibrium lattice constant are reported here. Also a brief discussion of the Fermi surface of ferromagnetic Ni3Pt is presented.