Hi, Erik,<br><br>Thanks for the information.<br><br>Regarding using more than two partial charges to mimic quadrupole explicitly, is there a one-to-one relation between the quadrupole moments and "position and magnitude" of the partial charges? For example, if I would like to include quadrupole moment for carbon in graphene, which has only non-zero Q20 quadrupole component, how should I place partial charges to mimic that quadrupole moment?<br>
<br>Any hint or direction for literature is appreciated.<br><br>Best,<br>Yanbin<br><br><div class="gmail_quote">On Thu, Jun 16, 2011 at 3:24 AM, Erik Marklund <span dir="ltr"><<a href="mailto:erikm@xray.bmc.uu.se">erikm@xray.bmc.uu.se</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Quadrupole interactions are implicit whenever you have a molecule withe more than two partial charges. You don't have to include it explicitly. There are, however, multipole expansion techniques to speed up electrostatics calculations, but that's another story.<br>
<br>
Erik<br>
<br>
15 jun 2011 kl. 23.45 skrev WU Yanbin:<br>
<div><div></div><div class="h5"><br>
> Dear GMXers,<br>
><br>
> Is there a way in GROMACS to include quadrupole-charge interaction?<br>
> Or is there a standard to way to mimic quadrupole moment using partial charge?<br>
><br>
> Thank you.<br>
><br>
> Best,<br>
> Yanbin<br>
</div></div>> --<br>
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-----------------------------------------------<br>
Erik Marklund, PhD student<br>
Dept. of Cell and Molecular Biology, Uppsala University.<br>
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