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<div style="margin-bottom: 0in;">Thanks a lot because of your attention. I
am trying to do phonon calculation in graphene so I think, having
well approximation for pseudo potential & exchange-correlation
one, will help you to achieve good frequencies which are compatible with
experiment.</div>
<div style="margin-bottom: 0in;">Now I think in VdW force you should
have segnificient changes in your core density, because of polarization. It
seems that situation could be same when we use full potential (Isn't
true?) 
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<div style="margin-bottom: 0in;">Best Regards</div>
<div style="margin-bottom: 0in;">Mehrnaz Anvari</div>
<div style="margin-bottom: 0in;">Iran University Of Science &
Technology 
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