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<div>Dear Stephan Rix:
<BR>
Apart from some convergence problems sometimes when the structure is far away from equilibrium, PWSCF can calculate the phonons for any structure in principle.
<BR>
Are you sure you have the very transition-state structure in your calculation of phonons?
<BR>
Are you sure there is a transition state in the reaction path specified by you?
<BR>
Transition state is also a saddle-point state, in which there is an imaginary vibrational mode along the migration coordinate with other modes being real. Thus, there should be an imaginary mode if the structure is in/close to the transition state.
<BR>
<BR>
Best Wishes!
<BR>
<BR>
Yours Sincerely
<BR>
L. F. Huang
<BR>
<BR>
</FONT><FONT color=#444444>> From: Stephan Rix
<BR>
</FONT><FONT color=#444444>> Subject: [Pw_forum] phonon modes for transition state
<BR>
</FONT><FONT color=#444444>> To: <A href=mailto:pw_forum@pwscf.org>pw_forum@pwscf.org</A>
<BR>
</FONT><FONT color=#444444>> Message-ID:
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</FONT><FONT color=#444444>>
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</FONT><FONT color=#444444>> Content-Type: text/plain; charset="iso-8859-1"
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</FONT><FONT color=#444444>>
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</FONT><FONT color=#444444>> Dear all,
<BR>
</FONT><FONT color=#444444>>
<BR>
</FONT><FONT color=#444444>> I am trying to calculate the phonon modes for a transition state using ph.x.
<BR>
</FONT><FONT color=#444444>>
<BR>
</FONT><FONT color=#444444>> I am expecting to find one negative/imaginary mode, but all resulting phonon
<BR>
</FONT><FONT color=#444444>> modes are positive.
<BR>
</FONT><FONT color=#444444>>
<BR>
</FONT><FONT color=#444444>> The transition state was optimized using pw.x with nudged elastic band and
<BR>
</FONT><FONT color=#444444>> climbing image.
<BR>
</FONT><FONT color=#444444>> Before running ph.x for the transition state I tested it with respect to
<BR>
</FONT><FONT color=#444444>> necessary thresholds on a fully relaxed equilibrium state and the results
<BR>
</FONT><FONT color=#444444>> were fine.
<BR>
</FONT><FONT color=#444444>>
<BR>
</FONT><FONT color=#444444>> Question: Is ph.x in principle capable of calculating transition state
<BR>
</FONT><FONT color=#444444>> phonon modes, i.e. returning negative/imaginary modes?
<BR>
</FONT><FONT color=#444444>> If so, I would appreciate any ideas or advice on how to obtain the desired
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</FONT><FONT color=#444444>> negative phonon mode.
<BR>
</FONT><FONT color=#444444>>
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</FONT><FONT color=#444444>> Thanks for your help.
<BR>
</FONT><FONT color=#444444>> Stephan
<BR>
</FONT><FONT color=#444444>>
<BR>
</FONT><FONT color=#444444>>
<BR>
</FONT><FONT color=#444444>> Stephan Rix
<BR>
</FONT><FONT color=#444444>> Dept. of Chemistry
<BR>
</FONT><FONT color=#444444>> Princeton University
<BR>
</FONT><FONT color=#444444>> Princeton, NJ 08540
<BR>
<BR>
<BR>
------
<BR>
======================================================================
<BR>
L.F.Huang(黄良锋) DFT and phonon physics
<BR>
======================================================================
<BR>
Add: Research Laboratory for Computational Materials Sciences,
<BR>
Instutue of Solid State Physics,the Chinese Academy of Sciences,
<BR>
P.O.Box 1129, Hefei 230031, P.R.China
<BR>
Tel: 86-551-5591464-328(office)
<BR>
Fax: 86-551-5591434
<BR>
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)
<BR>
<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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======================================================================
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