Structural properties of low-density liquid alkali metals

A AKANDE¹, G A ADEBAYO^1,2 and O AKINLADE²

¹The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy

²Department of Physics, University of Agriculture, Abeokuta, Nigeria

E-mail: aakande@ictp.trieste.it; gadebayo@ictp.trieste.it; akinlade@yahoo.com

Abstract. The static structure factors of liquid alkali metals have been modelled at

temperatures close to their melting points and a few higher temperatures

using the reverse Monte Carlo (RMC) method. The positions of 5000 atoms in

a box, with full periodicity, were altered until the experimental

diffraction data of the structure factor agrees with the associated model

structure factor within the errors. The model generated is then analysed.

The position of the first peak of the pair distribution function $g(r)$ does

not show any significant temperature dependence and the mean bond lengths

can be approximated within an interval

of 3.6--5.3 \AA, 4.5--6.6 \AA, 4.8--6.7 \AA\ and 5.1--7.3 \AA\

for Na, K, Rb and Cs respectively. The cosine bond distributions show

similar trend with the flattening up of the first peak with increase in

temperature. In addition, the coordination numbers of these liquid metals are

high due to the presence of non-covalent bonding between them. On the

average, we surmise that the coordination number decreases with increase in

temperature.

Keywords. Reverse Monte Carlo simulation; simple liquid; alkali metals; structure of liquid.

PACS Nos 61.20.Ja; 61.20.Ne; 02.70.-c