arXiv:astro-ph/9902264v1 18 Feb 1999 L A T E X A note on the thermal component of the equation of state of solids (Letter to the Editor) Vladan Celebonovic Institute of Physics,Pregrevica 118,11080 Zemun-Beograd,Yugoslavia (received: 15 November,1990) reference: Earth,Moon and Planets,54, pp.145-149 (1991). Abstract: A simple method for determining the thermal component of the EOS of solids under high pressure is proposed.Applications to the interior of the Earth gives results in agreement with recent geophysical data 1.Introduction Imagine a specimen of any chemical substance.In the case of a thermo- mechanical system,its equation of stae (EOS) will have the general form f (p,V,T ) = 0,where p,V,T denote,respectively the pressure to which the system is subjected,its volume and temperature. Proposing a realistic EOS for a given class of physical systems is,generally speaking a highly non-trivial problem (see,for instance,Eliezer et al.,1986; Schatzman and Praderie,1990 for details ).One usually starts from an as- sumed interparticle potential,determines the form of the Hamiltonian,and from it the thermodynamical functions and the EOS.In order to render the calculations more tractable,.the EOS is usually determined in form of isoterms in the p − V plane.The thermal component is often introduced at a later stage (for example,Holian,1986;Eliezer et al.,1986). 1