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

[K.A. Feenstra]

Erik Lindahl wrote:
> 
> I actually tried to "fix" this a long time ago, but it isn't trivial; we
> are summing a lot of charges, and due to the way they are represented in
> hardware they aren't exact. One option would of course be to only warn
> when the net charge is more than 0.01% of the system charge RMSD or
> something, but that might hide things like having one charged lipid
> among 1024 uncharged ones... I'll see if we attack it again.

I've though about this a bit a while ago. We possibly could re-set the
total charge after every charge-group, providing the total charge at 
that point is 'integer enough'? I.e. if we end up with 0.000001, we
re-set to zero, if we end up with 9.999999e-1 we re-set to 1. That 
would reduce the number charges summed at one time.


-- 
Groetjes,

Anton
 ________ ___________________________________________________________
|        | Anton Feenstra                                            |
| .      | Dept. of Pharmacochemistry - Vrije Universiteit Amsterdam |
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