• Lattice dynamical study of alkali metals: An unified approach based on CGW model

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    • Keywords

       

      Alkali metals; three-body forces; umklapp processes; dispersion curves; crossovers; specific heats

    • Abstract

       

      The phonon dispersion relations for lithium, sodium, potassium, rubidium and cesium along the principal symmetry directions as well as their lattice specific heats have been deduced using Clark, Gazis and Wallis angular force model. This model which conforms to the translational symmetry of the lattice, reproduces the observed crossover in lithium along [ζ00] direction at ζ = 0·49, without producing any crossovers in other alkali metals. Besides, the theoretical dispersion curves of all alkali metals are in excellent agreement with the corresponding experimental or homologous dispersion relations and theirϑD values compare well with the experimental values over a wide temperature range. It is shown that the strength of electron-ion interactions plays a significant role in the success of any unified lattice dynamical study of alkali metals while the three-body interactions of thecgw model do not. The importance of umklapp processes, failure of the earlier models to produce a crossover and the experimentalϑD-T curve in lithium as well as the apparent variation in the nature and range of atomic interactions of alkali metals are discussed.

    • Author Affiliations

       

      V Ramamurthy1 M Satishkumar1 2

      1. Department of Physics, Indian Institute of Technology, New Delhi - 110 016, India
      2. Department of Applied Physics, Regional Engineering College, Kurukshetra - 132 119, India
    • Dates

       
  • Pramana – Journal of Physics | News

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