High-Order Corrections and Its Effects on the Surface Tension of Simple Liquid Metals

The effect of high-order corrections to the usual secondorder perturbation theory has been demonstrated to be important in the literature. It appears that in the variational thermodynamic calculation based on the Gibbs-Bogoliubov inequality, although the choice of reference system is important and crucial in obtaining a reliable Helmholtz free energy, due attention must also be paid to the ‘true’ hamiltonian adopted in the theory. Motivated by this, we adopt a more reliable hamiltonian for calculating the surface tension of simple liquid metals. The effects of the above-noted corrections on the surface tension, derived using a full nonlocal pseudopotential, are examined and discussed.