Journal of Chemical and Engineering Data, Vol.58, No.7, 2083-2094, 2013
Universal Method for Approximating the Standard Thermodynamic Functions of Solids
The aim of this work is to offer an universal analytical description of the standard thermodynamic functions (primarily, C-p(o)(T), S-o(T), H-o (T) - H-o(T-r)), of solids with accuracy corresponding to experimental measurements. The main advantage of a semiempirical method of approximation under consideration consists in nonstandard usage of a linear combination of well-known thermodynamic functions of the harmonic oscillator (Planck-Einstein functions) unadjusted to the difference between isobaric and isochoric values. The article provides a description of the method, a brief theoretical analysis relating to its justification and opportunities, and examples of specific applications. The article focuses on the problem related to the practical application of thermodynamic data, the problem of Standard representation of standard thermodynamic functions themselves. If the substance under investigations does not undergo phase transformations within the temperature interval (0 to T) K and the reference temperature T-r <= T then the S-o (T) and H-o (T)-H-o(T-r) functions are easy to calculate on the basis of the values of C-p(o)(T) and "frozen" configuration contributions to entropy if they exist. For this reason, much attention is paid to the dependence Of the heat capacity of solids on the temperature.