<div dir="ltr">Hi,<div><br></div><div>yes, thank you for your reply. Appropriately modifying the Coulomb cutoff is what we found out as well. And it makes sense, because electrostatic interactions are computed with classical Coulomb formula with cutoff. Since we had default large cutoff, (much larger than c/2, c is box size), particles would see several images of others, introducing artifacts into the calculation.</div><div><br></div><div>Thank you.</div><div>best,</div><div>stanislav.<br><br>On Monday, November 6, 2017 at 6:24:15 PM UTC+1, jgh wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;">Hi
<br>
<br>SE periodic calculations are non trivial, as there are many options
<br>and no fully tested default values.
<br>I have done a calculation as described in your mail and I get
<br>consistent results for the Mulliken charges of approx.
<br>O -0.610
<br>H  0.305
<br>
<br>My input is attached.
<br>
<br>regards
<br>
<br>Juerg Hutter
<br>
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<br>From: Stanislav Šimko 
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<br>Date: 11/02/2017 09:47AM
<br>Subject: [CP2K:9616] PM6 Mulliken charges
<br>
<br>Dear Cp2k users,
<br>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:
<br>
<br>      h2o              triple h2o
<br>Ox        6.184751      6.697106
<br>Hy        0.905911      0.642258
<br> Hy        0.909339      0.660701
<br>
<br>Can anyone clarify why is this happening? I would expect that I obtain the same results.
<br>Thank you for the help!
<br>
<br>Stanislav
<br>  
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