Dear Huang,<br><br>You are the best person to guess the best initial path. What I would suggest is to get an idea as to how the H atom diffuses (either by searching literature or from some chemical insight) and provide the guess path by specifying the intermediate images with the option "intermediate_image". This way the code uses your guess path rather than doing an interpolation.<br>
<br>Prasenjit.<br><br><div class="gmail_quote">2009/3/30 lfhuang <span dir="ltr"><<a href="mailto:lfhuang@theory.issp.ac.cn">lfhuang@theory.issp.ac.cn</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<div>Dear Paolo Giannozzi and Prasenjit Ghosh:
<br>
Thank you for your kind attention!
<br>
I view the initial path in xcrysden, which should mean this is not related to the QE version (am I right?), And
<br>
there are some C atoms even displace over several lattice constants or substituted by the H adatom. From other
<br>
literatures, the H atom should diffuse along the C-C bond, based on which I added 3-7 intermediate images, but
<br>
that doesn't make any different!
<br>
Although in the first and last images, as P. Giannozzi mentioned, the C atoms are somewhat distorted by the
<br>
H adatom, the displacement of them are small (less than 0.5 angstroms, the lattice constant is 2.5).
<br>
So I want to ask, when you meet this kind of failure of the interpolation for the initial path, what would you
<br>
do to get an reasonable one? Thanks!
<br><div class="im">
<br>
Best Wishes!
<br>
<br>
Yours Sincerely
<br>
L. F. Huang
<br>
<br>
</div><font color="#444444">> Date: Sun, 29 Mar 2009 19:54:17 +0200
<br>
</font><font color="#444444">> From: Paolo Giannozzi
<br>
</font><font color="#444444">> Subject: Re: [Pw_forum] a not reasonable initial path for NEB
<br>
</font><font color="#444444">> calculation
<br>
</font><font color="#444444">> To: PWSCF Forum
<br>
</font><font color="#444444">> Message-ID:
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</font><font color="#444444">> Content-Type: text/plain; charset="us-ascii"
<br>
</font><div class="im"><font color="#444444">>
<br>
</font><font color="#444444">>
<br>
</font><font color="#444444">> On Mar 29, 2009, at 16:14 , lfhuang wrote:
<br>
</font></div><div class="im"><font color="#444444">> </font><font color="#444444">> I am calculating the diffusion barrier of atomic H on graphene
<br>
</font><font color="#444444">> </font><font color="#444444">> layer using NEB method. The first_image and last_image correspond
<br>
</font><font color="#444444">> </font><font color="#444444">> to structures with a H atom on top of two nearest C atoms,
<br>
</font><font color="#444444">> </font><font color="#444444">> respectively. However, the interpolated initial path is not
<br>
</font><font color="#444444">> </font><font color="#444444">> reasonable that there are some largely displaced C atoms in the
<br>
</font></div><font color="#444444">> </font><font color="#444444">> configurations between first and last images, because [...]
<br>
</font><div class="im"><font color="#444444">> >
<br>
</font><font color="#444444">> ...the C atom in the first and the last image were not ordered in the
<br>
</font><font color="#444444">> same way.
<br>
</font></div><div class="im"><font color="#444444">> </font><font color="#444444">> In addition, I use the QE-3.2.3 version
<br>
</font><font color="#444444">> >
<br>
</font></div><div class="im"><font color="#444444">> no longer supported, use it at your own risk.
<br>
</font></div><div class="im"><font color="#444444">> </font><font color="#444444">> Could anyone help me? I'd like to appreciate any good advice!
<br>
</font><font color="#444444">> >
<br>
</font><font color="#444444">>
<br>
</font></div><div class="im"><font color="#444444">> I think xcrysden should be able to visualize the path
<br>
</font><font color="#444444">>
<br>
</font><font color="#444444">> P.
<br>
</font><font color="#444444">> ---
<br>
</font><font color="#444444">> Paolo Giannozzi, Democritos and University of Udine, Italy
<br>
<br>
</font></div><font color="#444444">> Message: 7
<br>
</font><font color="#444444">> Date: Sun, 29 Mar 2009 20:49:09 +0200
<br>
</font><font color="#444444">> From: Prasenjit Ghosh
<br>
</font><font color="#444444">> Subject: Re: [Pw_forum] a not reasonable initial path for NEB
<br>
</font><font color="#444444">> calculation
<br>
</font><font color="#444444">> To: PWSCF Forum
<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="gb2312"
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</font><div class="im"><font color="#444444">>
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</font><font color="#444444">> if u have some approximate idea of the path, u can provide the guess path by
<br>
</font><font color="#444444">> mentioning the images using the option "intermediate image" in the card
<br>
</font><font color="#444444">> ATOMIC_POSITIONS
<br>
</font><font color="#444444">>
<br>
</font><font color="#444444">> Prasenjit.
<br>
</font></div><font color="#444444">>
<br>
<br>
------
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<br><div class="im">
L.F.Huang(»ÆÁ¼·æ) <a href="mailto:lfhuang@theory.issp.ac.cn" target="_blank">lfhuang@theory.issp.ac.cn</a>
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<br></blockquote></div><br><br clear="all"><br>-- <br>PRASENJIT GHOSH,<br>POST-DOC,<br>ROOM NO: 265, MAIN BUILDING,<br>CM SECTION, ICTP,<br>STRADA COSTERIA 11,<br>TRIESTE, 34104,<br>ITALY<br>PHONE: +39 040 2240 369 (O)<br>
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