When doing structure minimization, I need to calculate a series of structures. Is it fine to set different Muffin-Tin sphere for different calculations. I believe it is fine because I am not comparing them with each other. Is it?<br>
<br><br>Yundi<br><br><div class="gmail_quote">On Thu, Sep 1, 2011 at 12:41 PM, Laurence Marks <span dir="ltr"><<a href="mailto:L-marks@northwestern.edu">L-marks@northwestern.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Yes, much to large.<br>
<br>
Read the FAQ on minimization, you are doing something wrong.<br>
<br>
2011/9/1 Yundi Quan <<a href="mailto:quanyundi@gmail.com">quanyundi@gmail.com</a>>:<br>
<div><div></div><div class="h5">> Thanks for you reply. My minimization stops with a message saying that the<br>
> force is minimized and the force and energy are inconsistent. So I carried<br>
> out another calculation by using the structure file that I got. However, the<br>
> force on one of the atoms is as large as 26. Is it too large to be used as a<br>
> equilibrium state?<br>
> Thanks a lot.<br>
> Yundi<br>
><br>
> 2011/8/31 å×ÇÅÎÉÑ ëÁÂÌÉÍÁÎ <<a href="mailto:evgeniya@theochem.tuwien.ac.at">evgeniya@theochem.tuwien.ac.at</a>><br>
>><br>
>> I mean minimization of internal parameters (lattice coordinates) in your<br>
>> initial structure. This is a crucial point. You should not have forces on<br>
>> atoms, since it is a kind of reference state. The structure optimization<br>
>> (lattice parameters) itself is less crucial as long as you have the<br>
>> reasonable lattice parameters.<br>
>><br>
>> Once you have a well relaxed structure, you can construct atomic<br>
>> displacements and calculate 'total forces' using force convergence criteria<br>
>> (-fc) at fixed lattice constants.<br>
>><br>
>> Total forces, which you need for phonon calculations, are the derivatives<br>
>> of total energies with respect to atomic displacements. Therefore, in order<br>
>> to get more precise values of total forces one usually constructs big<br>
>> supercells. This means that a size of your supercell is also important.<br>
><br>
><br>
>><br>
>><br>
>><br>
>> 2011/8/31 Yundi Quan <<a href="mailto:quanyundi@gmail.com">quanyundi@gmail.com</a>><br>
>>><br>
>>> By relaxing structure, do you mean internal structure or the crystal<br>
>>> structure or both?<br>
>>><br>
>>> Yundi<br>
>>><br>
>>> 2011/8/31 å×ÇÅÎÉÑ ëÁÂÌÉÍÁÎ <<a href="mailto:evgeniya@theochem.tuwien.ac.at">evgeniya@theochem.tuwien.ac.at</a>><br>
>>>><br>
>>>> Fisrt you have to relax your structure until you have no forces on all<br>
>>>> your atoms. Then you create the displacements and perform scf calculations<br>
>>>> without minimization.<br>
>>>><br>
>>>> 2011/8/31 Yundi Quan <<a href="mailto:quanyundi@gmail.com">quanyundi@gmail.com</a>><br>
>>>>><br>
>>>>> Hi, When doing phonon calculation, do I have to do structure<br>
>>>>> minimization first?<br>
>>>>> Yundi<br>
>>>>> _______________________________________________<br>
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>>>>><br>
>>>><br>
>>>><br>
>>>><br>
>>>> --<br>
>>>> Evgeniya Kabliman.<br>
>>>> Insitute of Materials Chemistryš š š šš Vienna University of Technology<br>
>>>> Getreidemarkt 9/165-TC, A-1060 Vienna, Austria<br>
>>>> Tel: <a href="tel:%2B43%201%2058801%2015674" value="+4315880115674">+43 1 58801 15674</a>š š š š Fax: <a href="tel:%2B43%201%2058801%2015698" value="+4315880115698">+43 1 58801 15698</a><br>
>>>> <a href="mailto:evgeniya@theochem.tuwien.ac.at">evgeniya@theochem.tuwien.ac.at</a>š š š š š <a href="http://www.imc.tuwien.ac.at" target="_blank">http://www.imc.tuwien.ac.at</a><br>
>>>><br>
>>>> _______________________________________________<br>
>>>> Wien mailing list<br>
>>>> <a href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br>
>>>> <a href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien" target="_blank">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br>
>>>><br>
>>><br>
>>><br>
>>> _______________________________________________<br>
>>> Wien mailing list<br>
>>> <a href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br>
>>> <a href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien" target="_blank">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br>
>>><br>
>><br>
>><br>
>><br>
>> --<br>
>> Evgeniya Kabliman.<br>
>> Insitute of Materials Chemistryš š š šš Vienna University of Technology<br>
>> Getreidemarkt 9/165-TC, A-1060 Vienna, Austria<br>
>> Tel: <a href="tel:%2B43%201%2058801%2015674" value="+4315880115674">+43 1 58801 15674</a>š š š š Fax: <a href="tel:%2B43%201%2058801%2015698" value="+4315880115698">+43 1 58801 15698</a><br>
>> <a href="mailto:evgeniya@theochem.tuwien.ac.at">evgeniya@theochem.tuwien.ac.at</a>š š š š š <a href="http://www.imc.tuwien.ac.at" target="_blank">http://www.imc.tuwien.ac.at</a><br>
>><br>
>> _______________________________________________<br>
>> Wien mailing list<br>
>> <a href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br>
>> <a href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien" target="_blank">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br>
>><br>
><br>
><br>
> _______________________________________________<br>
> Wien mailing list<br>
> <a href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br>
> <a href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien" target="_blank">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a><br>
><br>
><br>
<br>
<br>
<br>
--<br>
</div></div>Laurence Marks<br>
Department of Materials Science and Engineering<br>
MSE Rm 2036 Cook Hall<br>
2220 N Campus Drive<br>
Northwestern University<br>
Evanston, IL 60208, USA<br>
Tel: <a href="tel:%28847%29%20491-3996" value="+18474913996">(847) 491-3996</a> Fax: <a href="tel:%28847%29%20491-7820" value="+18474917820">(847) 491-7820</a><br>
email: L-marks at northwestern dot edu<br>
Web: <a href="http://www.numis.northwestern.edu" target="_blank">www.numis.northwestern.edu</a><br>
Research is to see what everybody else has seen, and to think what<br>
nobody else has thought<br>
Albert Szent-Gyorgi<br>
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</div></div></blockquote></div><br>