https://doi.org/10.1140/epjb/e2012-20908-6
Regular Article
Analytic equation of state and thermodynamic properties for solid FCC C60 over a wide range of pressures and temperatures
1
School of Electronic information Engineering, University of
Chengdu, Chengdu,
Sichuan
610106, P.R.
China
2
Department of Applied Physics, University of Electronic Science
and Technology, Chengdu, Sichuan
610054, P.R.
China
3
Department of Physics, A’ ba Teachers College, Chengdu, Sichuan
611741, P.R.
China
a e-mail: yangweiuestc@yahoo.cn
Received:
7
November
2011
Received in final form:
13
April
2012
Published online:
12
June
2012
As an analytic approximation to the free volume theory (FVT), the analytic mean field potential (AMFP) approach is applied to the multi-exponential model solid. The analytic expressions for the equation of state (EOS) and thermodynamic quantities are derived. The formalism for the case of the double-exponential (DE) model is applied to the solid fcc C60. The four potential parameters are determined by fitting the experimental data of cohesive energy, lattice constant and compression curve of solid C60. The numerical results calculated show that the Girifalco potential is too hard and gives compression curve prominently deviated from experiments at high pressure, whereas the DE potential can well describe the thermo-physical properties of C60 system within wide pressure range. The calculated variation of lattice constant versus temperature relationship and compression curve for solid C60 by using the DE potential agree well with experimental data available. Especially the AMFP with DE potential predicted that the fcc C60 solid is stable up to 2440 K, the spinodal temperature, in good agreement with the result from molecular dynamic (MD) simulation. The AMFP is a useful approach to consider the anharmonic effects at high temperature for solid C60.
Key words: Mesoscopic and Nanoscale Systems
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2012