Papers by Author: Sanjeev K. Gupta

Abstract: A detailed theoretical study of structural, electronic and vibrational properties of niobium carbide are carried out in rocksalt phase using the density functional theory implemented in ABINIT code. The calculated structural parameters like lattice constant and bulk modulus agree well with the available data. The Zener anisotropy factor (A), Poison's ratio (v), Young’s modulus (Y) and shear modulus (C’) are also presented. The electronic band structure and density of states are presented and discussed in light of bonding nature in NbC. The band structure indicates its metallic nature. The calculated phonon dispersion curves show that the NbC in rocksalt phase has all positive phonons throughout the Brillouin zone. The thermodynamical properties are also presented and discussed.

Abstract: The present paper presents the carrier-acoustic phonon scattering rate and charge transport in spherical and TMV viruses. We demonstrate theoretically that the absorption rate changes according to the phonon energy while emission of phonon is limited by the both electron and hole energy. The obtained conductivity for spherical and TMV viruses suggest that the TMV virus is more conducting and therefore may be a good candidate for the connector or wire to be used in the nano- and molecular- electronics . The value of resistance obtained for TMV virus is lower than the resistance of DNA.

Abstract: The present paper reports a simple calculation of the size and shape dependent melting temperature of nanoparticles. The melting temperature of any nanoparticle basically depends on the ratio of surface atoms to the total atoms. Significant melting temperature suppression is observed when the particle size approaches the sub-20 nm range. The behavior of melting temperature is similar for the larger nanoparticles of all considered shapes but differs significantly for small nanoparticles. Different melting temperature is predicted for the nanoparticles of the same size in different shapes.