• A R Jani

      Articles written in Pramana – Journal of Physics

    • Phonon dispersion in cubic transition metals: A comparison between Fielek and extended Cheveau models

      V B Gohel A R Jani

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      Phonon dispersion in bcc transition metals has been studied by Fielek and extended Cheveau models. A comparative study of the results shows that the wavy nature of [ξ00]-L branch in the dispersion curves of some metals is due to the long range forces which are well accounted for by the extended Cheveau model but not by the Fielek model. The peculiar behaviour of transverse branches are due to the presence ofd-electrons. It is found that the oscillatingd-shell model of Fielek is fairly good for tungsten, α-iron and molybdenum, but does not give satisfactory description ofd-electron effects in the remaining bcc transition metals.

    • Superconducting state parameters of indium-based binary alloys

      A M Vora Minal H Patel P N Gajjar A R Jani

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      Our well-recognized pseudopotential is used to investigate the superconducting state parameters viz: electron-phonon coupling strength λ. Coulomb pseudopotential μ*, transition temperature Tc, isotope effective exponent α and interaction strength N0V for the In1−xZnx and In1−xSnx binary alloys. We have incorporated six different types of local field correction functions, proposed by Hartree, Taylor, Vashistha-Singwi, Ichimaru-Utsumi, Farid et al and Sarkar et al to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of the various exchange and correlation functions is concluded from the present study. The comparison with other such theoretical values is encouraging, which confirms the applicability of our model potential in explaining the superconducting state parameters of binary mixture.

    • Lattice mechanical properties of some fcc f-shell metals

      J K Baria A R Jani

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      A pseudopotential depending on an effective core radius is proposed to study the binding energy, equation of state, ion-ion interaction, phonon dispersion curves (q-space and r-space analysis), mode Grüneisen parameters and dynamical elastic constants of some fcc f-shell metals La, Yb, Ce and Th. The contribution of the s-like electrons is calculated in the second-order perturbation theory for the potential while d and f-like electron is taken into account by introducing repulsive short-range Born-Mayer term. The parameter of the potential is evaluated by zero pressure condition. An excellent agreement between theoretical investigations and experimental findings is achieved which confirms the present formalism

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