• G P Srivastava

      Articles written in Pramana – Journal of Physics

    • Anharmonic relaxation of phonons

      G P Srivastava

      More Details Abstract Fulltext PDF

      Using the Ziman scheme of considering a drifting Planck’s distribution, as the eigenvector of the linearized phonon collision operator, the anharmonic relaxation of phonons is discussed. The earlier arbitrariness in the phonon-phonon coupling parameters is removed by formulating explicit expressions for different allowed processes in terms of measurable quantities. Low and high temperature approximations of relaxation rates are also discussed: the results differ from earlier calculations. At low temperatures superthermal or high frequency phonons, which have temperature-independent and equal N- and U-relaxation rates, play important roles in thermal conduction in pure insulators.

    • Calculations of anharmonic phonon relaxation times

      G P Srivastava

      More Details Abstract Fulltext PDF

      Anharmonic phonon relaxation times in Ge are calculated using (i) an isotropic continuum model, and (ii) a dispersive model. A complete spectrum of calculated results is presented. Frequency-averaged values for normal- and umklapp-three-phonon relaxation times are also calculated. A comparison is made between our findings and some earlier works, and disagreements are discussed. The results are applied in calculating some results in the theory of lattice thermal conductivity.

    • Comparison of high-temperature three-phonon resistivities from different theoretical models

      G P Srivastava

      More Details Abstract Fulltext PDF

      We present a comparison of high-temperature three-phonon resistivities from the relaxation time methods due to Klemens, Callaway, and Debye, and the variational method due to Leibfried and Schlömann. All the calculations are based upon the same choice of anharmonic crystal potential; and hence the results are suitable for comparison on quantitative basis. We find that the resistivities in increasing order of magnitude come from the methods due to Klemens, Callaway Debye, and Leibfried and Schlömann respectively.

  • Pramana – Journal of Physics | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.