An isothermal equation of state of solid

In this paper, an isothermal three-parameter equation of state (EOS) of solid is proposed in the form V/V-0 = f(P), with pressure P as the independent and relative volume V/V-0 as the dependent variable. The proposed EOS uses three parameters expressible in terms of B-0, B-0' and B-0", denoting bulk modulus and its first and second pressure derivatives at zero pressure. The new model is applied to the isotherms of ionic, metallic, quantum and rare-gas solid, with pressures ranging from zero to variable maximum pressures of up to 1 TPa. the fits are uniformly excellent. Root-mean-square deviations between data and fits are computed and compared with the three-parameter empirical EOS proposed by Kumari and Dass [J. Phys.: Condens. Matter 2, 3219 (1990)]. It is shown that our new form yields a decisively superior fit. Furthermore, it is shown that our proposed equation of state has an advantage for some close-packed materials because it allows B-infinity' = (deltaB(s)/deltaP)(s) (P --> infinity) to be fitted, and this is where the usual standard equations fail badly.