NaCl-KCl

Abstract

First principles phase diagram calculations were performed for the system NaCl-KCl. Planewave pseudopotential calculations of formation energies were used as a basis for fitting cluster expansion Hamiltonians, both with- and without an approximation for the excess vibrational entropy (SV IB). Including SV IB dramatically improves the agreement between calculated and experimental phase diagrams: experimentally, the consolute point is {XC = 0.348, TC = 765K}Exp; without SV IB, it is {XC = 0.46, TC 1630K}Calc; with SV IB, it is {XC = 0.43, TC 930K}Calc. Key words: NaCl-KCl; First Principles; Phase diagram calculation; Excess vibrational entropy; insulator; ionic system.