Heat of mixing of equiatomic alkali-alkali alloys

The Gibbs-Bogoliubov variational technique is used to study the internal energy and entropy of liquid alkali metals as well as heat of mixing and excess entropy of mixing for equiatomic NaK, KRb and NaCs alloys. A Heine-Abarenkov-type model potential has been considered with Hartree, Hubbard-Sham and Vashishta-Singwi exchange and correlation functions. It is found that alloying properties are sensitive to the form of the potential used, the dielectric screening function and the volume of mixing.