<br clear="all">Dear Manjo<div><br></div><div>The forces between two permanent dipoles and a permanent dipole and a corresponding induced dipole are usually larger than two instantaneously induced dipoles. So I expect that DFT and especially DFT-D can see the two first mentioned forces better than the latter. You can make a clever set of molecules that their Inter-molecular forces change and calculate the energy once with DFT-D and another time with pure DFT. Then you can understand that which of the approaches can predict the trend well. You 'd better not care about absolute values and just check the trend. I hope it helps. </div>
<div><br></div><div><br> Best Wishes, m<br><br> <br> <br><br><br>----------------------------------------<br>
Masoud Nahali<br>SUT<br><a href="mailto:masoud.nahali@gmail.com" target="_blank">masoud.nahali@gmail.com</a> <br><a href="http://alum.sharif.edu/~m_nahali" target="_blank">alum.sharif.edu/~m_nahali</a> <div><br><br></div>
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<br><br><div class="gmail_quote">On Sun, Aug 12, 2012 at 6:06 PM, Manoj wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
<br>
Dear Masoud<br>
Thank you for your reply, but what my doubt is<br>
that QE only includes london dispersion. What about other effects like<br>
Keesom and Debye forces ?<br>
<br>
Yours Sincerely<br>
Manoj<br>
<br><br>
</blockquote></div><br></div>