Dear Ghosh,<div>Thanks for you explanation. Now I got it.</div><div>I have another problem. After running 'min ....', I got a structure with very small force. However, when I do another calculation with the structure I got, the total force on each atom becomes very large. What is the reason for this?</div>
<div><br></div><div><br></div><div>Yundi</div><div><br><div class="gmail_quote">On Mon, Sep 26, 2011 at 7:44 PM, Ghosh SUDDHASATTWA <span dir="ltr"><<a href="mailto:ssghosh@igcar.gov.in">ssghosh@igcar.gov.in</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Dear Yundi,<br>
If I understand your question correctly, then just by doing step 1, you<br>
cannot get energy minimum but by doing the following<br>
1. Optimize lattice parameters<br>
2. use optimized lattice parameters and then min_lapw<br>
3. Use optimized lattice parameters and optimized atomic positions and get<br>
ENE (including -so or any other options)<br>
<br>
Only after step 3, can you say that you have energy minimum.<br>
<div class="im"><br>
-----Original Message-----<br>
From: <a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a><br>
[mailto:<a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a>] On Behalf Of Yundi Quan<br>
</div>Sent: Monday, September 26, 2011 9:25 PM<br>
<div class="im">To: A Mailing list for WIEN2k users<br>
</div>Subject: Re: [Wien] phonon calculation<br>
<div><div></div><div class="h5"><br>
In the second step, what if the total energy changes with the internal<br>
structure so that the so-called energy minimum found in step one is no<br>
longer a energy minimum?<br>
<br>
Yundi<br>
<br>
2011/9/26 Ghosh SUDDHASATTWA <<a href="mailto:ssghosh@igcar.gov.in">ssghosh@igcar.gov.in</a>>:<br>
> Dear Yundi,<br>
> What I follow is<br>
> 1. do volume or c/a, b/a relaxation depending on your structure<br>
> 2. Use the optimized lattice parameters to do min_lapw<br>
> 3. Use the optimized lattice parameters and atomic positions to define the<br>
> supercell in Phonon software<br>
> 4. import the d45 file from phonon to wien2k<br>
> 5. run phonon.job in wien2k<br>
> 6. get the force file and export it to phonon<br>
> 7. get the phonon dispersion<br>
><br>
> you can use -fc 1.0 in min_lapw as well as in phonon. you can then try -fc<br>
> 0.50 and then so on<br>
><br>
> SG<br>
><br>
> ________________________________<br>
> From: <a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a><br>
> [mailto:<a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at">wien-bounces@zeus.theochem.tuwien.ac.at</a>] On Behalf Of Yundi Quan<br>
> Sent: Monday, September 26, 2011 3:41 PM<br>
> To: A Mailing list for WIEN2k users<br>
> Subject: [Wien] phonon calculation<br>
><br>
> In order to get the correct input structure for phonon calculation, I need<br>
> to first find the structure with minimal force. How much force is small<br>
> enough? Is 1.0 mRy/bohr small enough? (I only want to calculate the phonon<br>
> at gamma point to see whether the system is stable or not at gamma point)<br>
> Should I first carry out internal structure minimization or crystal<br>
> structure minimization?<br>
><br>
><br>
> Yundi<br>
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><br>
><br>
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