Hi all, I've learned that the single-point energy calculation (calculation='scf') can be used for the following purpose:
--------- It can be used to calculate an equation of state (i.e. a pressure-volume and/or energy-volume dependence) for high-symmetry systems with no internal degrees of freedom, as long as the Stress property is specified. --------- But I've some puzzles on the meaning of internal degrees of freedom. Say, for a bcc structure, does it has internal degrees of freedom or not? Furthermore, in the general case, how can I know whether a system has the internal degrees of freedom or not? ps. According to the paper J. Phys.: Condens. Matter 21 395502, the internal degrees of freedom, also can be called the microscopic degrees of freedom, is the atomic coordinates; and the macroscopic degrees of freedom are the shape and size of the unit cell. -- Hongsheng Zhao <zhaohscas at yahoo.com.cn> School of Physics and Electrical Information Science, Ningxia University, Yinchuan 750021, China
