On Dec 24, 2010, at 7:56 , Riping WANG wrote: > In example18, for cp.x practice. I found the " ion_radius(1) > and ion_radius(2) " in the input file. > Could you please tell me something about this input parameter, and > how to set?
usuallly you do not need to set it: the default value should be fine. ion_radius is the width of a gaussian distribution of charge replacing the point charge of the (pseudo-)nucleus. It should be big enough to ensure convergence of the total energy in G-space, small enough to yield negligible overlap between gaussians. Valus around 0.8 are usually fine. The total energy and forces should not change if ion_radius changes. P. --- Paolo Giannozzi, Dept of Chemistry&Physics, Univ. Udine via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
