[gmx-users] Again: Non-integer charges in tpr-files

[K.A. Feenstra]

Erik Lindahl wrote:
> 
> Won't work, since we don't request that all charge groups are strictly
> neutral. It's only with cutoffs that the neutrality is important, but
> the concept of charge groups still speeds up neighborsearching quite a lot.

Ok, then what about this (you probably thought about this also, but 
anyway): in sum_q in topio.c, the charges are summed as follows:

    *qt  += n*atoms->atom[i].q;

qt is *double, but t_atom.q is a float. Is the increment then done in 
double or single precision? Or is that not defined?


-- 
Groetjes,

Anton
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