giannozz at democritos.it
Fri Dec 24 09:56:00 CET 2010
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
Paolo Giannozzi, Dept of Chemistry&Physics, Univ. Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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