PM6 Mulliken charges

Stanislav Šimko stanisl... at
Thu Nov 2 08:47:00 UTC 2017

Dear Cp2k users,
I've wanted to do some calculations using periodic PM6 and calculate 
Mulliken charges, however, I got some weird results. I compared atomic 
charges of two systems - in the first one I've got a single water molecule 
in a periodic box (~14A box), and in the other one the same situation is 
triplicated in all three directions (still periodic, ~42A). So the geometry 
of the system is the same in both cases, but the computed atomic charges 
are not the same:

      h2o              triple h2o
Ox 6.184751      6.697106
Hy 0.905911      0.642258
Hy 0.909339      0.660701

Can anyone clarify why is this happening? I would expect that I obtain the 
same results.
Thank you for the help!

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