CHINESE ACAD SCI,STATE KEY LAB SCI & ENGN COMP,BEIJING 100080,PEOPLES R CHINA
英文摘要:
The hydrogen bonded ammonia chain model is studied by means of the standard self-consistent phonon approach and two modified versions. The effective crystal constant, force constant, free energy, and ratio of the first-order free energy to the zero order as a function of temperature are numerically obtained with the three approaches, and then compared. The standard approach gives the lowest free energy. Violation of the convexity is found in one of the modified approaches near the temperature which is regarded as the melting temperature.
