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<div>Dear P. B. Sorokin:
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</FONT><FONT color=#444444>> But when I try to evaluate the velocity I obtain the answer nearly in
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</FONT><FONT color=#444444>> six time less then reported early: 2200 m/s and 3400 m/s vs. 12200
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</FONT><FONT color=#444444>> m/s and 19500 m/s.
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</FONT><FONT color=#444444>> I do some stupid mistake, but where? Does anybody has the experience
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</FONT><FONT color=#444444>> in such calculations?
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Where does your reference for the sound velocity come from? And there are 3 acoustic bands for graphene, one of which is the bending mode with a parabolic dispersion near gamma point. Have you pay attention to this band?
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Best Wishes!
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Yours Sincerely
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L.F.Huang
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L.F.Huang(黄良锋) DFT and phonon physics
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Add: Research Laboratory for Computational Materials Sciences,
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Instutue of Solid State Physics,the Chinese Academy of Sciences,
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P.O.Box 1129, Hefei 230031, P.R.China
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Tel: 86-551-5591464-328(office)
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Fax: 86-551-5591434
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Web: <A href=http://theory.issp.ac.cn target=_blank>http://theory.issp.ac.cn</A</FONT><FONT color=#444444>> (website of our theory group)
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<A href=http://www.issp.ac.cn target=_blank>http://www.issp.ac.cn</A</FONT><FONT color=#444444>> (website of our institute)
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