Molecular dynamics study of the structure of expanded liquid rubidium and caesium

K. W. Cheng, H. C. Chen, S. K. Lai

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4 Scopus citations

Abstract

The temperature/density dependences of the structure of expanded liquid metals rubidium and caesium have been calculated along the liquid-vapour coexistence curve using the molecular dynamics technique. In contrast to previous simulation studies, we adopt a full density dependent pairwise potential constructed from a highly reliable and accurate non-local model pseudopotential. For both liquid alkali metals, we find that our Fourier-transformed liquid structure factors generally agree quite well with the neutron diffraction data for the wave number ∼0.6 Å-1 and above, whereas for thermodynamic states near the critical point and for wave numbers smaller than ∼0.6 Å-1 we observe large discrepancies which we are unable to account for adequately in the present work. Nevertheless, by examining and comparing the variation of our calculated pair potential as well as the liquid structure factor with temperature/density, our present results provide further information on the validity of nearly-free-electron theory notably for thermodynamic states approaching the critical regime. Specifically, we conjecture break-down temperatures possibly occurring at T ≈ 1700 K and T ≈ 1600 K for liquid rubidium and caesium metals, respectively.

Original languageEnglish
Pages (from-to)125-132
Number of pages8
JournalPhysica B: Condensed Matter
Volume179
Issue number2
DOIs
StatePublished - 1 Jun 1992

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