Collect. Czech. Chem. Commun. 1981, 46, 542-551

Use of the Padé approximants for calculating the second virial coefficient

Tomáš Boublík and Jan Vosmanský

Institute of Chemical Process Fundamentals, Czechoslovak Academy of Sciences, 165 02 Prague 6-Suchdol


The expansions in reduced temperature, occurring in relations for the second virial coefficient of the power-law potentials were expressed by the Pade approximant. For the Kihara potential it is proved that the functions F1(T*), F2(T*) and F3(T*) and consequently the whole virial coefficient can bee expressed for reduced temperatures T* 0.6 with a good accuracy by means of a simple Pade approximant. To describe quantum effects on the second virial coefficient of low-molecular gases at low temperatures a simple approximant was formulated on the basis of the Wigner-Kirkwood expansion allowing to correlate data on the second virial coefficient even in the temperature range where the use of the Wigner-Kirkwood expansion already fails.