Both cases are very converged. One gives magnetic solution. The other gives non-magnetic solution. The magnetic solution is slightly lower in energy. <div><br></div><div><br></div><div><br><br><div class="gmail_quote">On Thu, Feb 16, 2012 at 4:48 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:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Maybe, or maybe not! If both cases are well converged, that means that<br>
for your approximations there are two locally stable spin states.<br>
Maybe this is real, maybe not, that is hard to say.<br>
<br>
2012/2/16 Yundi Quan <<a href="mailto:quan@ms.physics.ucdavis.edu">quan@ms.physics.ucdavis.edu</a>>:<br>
<div><div></div><div class="h5">> You are right. The spin state is different in two cases. Applying U after a<br>
> scf calculation seems to tend to reduce the magnetic moments.<br>
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> On Thu, Feb 16, 2012 at 3:44 PM, Laurence Marks <<a href="mailto:L-marks@northwestern.edu">L-marks@northwestern.edu</a>><br>
> wrote:<br>
>><br>
>> If all other things are the same, the lowest energy is correct<br>
>> (variational principle). Probably the spin state is different in the<br>
>> two cases.<br>
>><br>
>> But...please ensure that you really have both converged. Assuming that<br>
>> you have a recent version, do a "grep -e :MV case.scf" (with case<br>
>> replaced as appropriate). The % value should be small for true<br>
>> convergence; if it is not you do not have real convergence<br>
>> (technically it is called a "trap").<br>
>><br>
>> 2012/2/16 Yundi Quan <<a href="mailto:quanyundi@gmail.com">quanyundi@gmail.com</a>>:<br>
>> > Dear Sir/Madam,<br>
>> > When using LSDA+U, it is recommended to first do an LSDA caculation and<br>
>> > then<br>
>> > turn on U. I first did an LSDA calculation to convergence. Then, I<br>
>> > turned on<br>
>> > U. I also did a calculation by turning on U from the very beginning. I<br>
>> > compared the two results, and found that the later is lower in energy.<br>
>> > Which<br>
>> > one is correct?<br>
>> ><br>
>> ><br>
>> ><br>
>> ><br>
>> ><br>
>> > _______________________________________________<br>
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>> ><br>
>><br>
>><br>
>><br>
>> --<br>
>> Professor Laurence Marks<br>
>> Department of Materials Science and Engineering<br>
>> Northwestern University<br>
>> <a href="http://www.numis.northwestern.edu" target="_blank">www.numis.northwestern.edu</a> <a href="tel:1-847-491-3996" value="+18474913996">1-847-491-3996</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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><br>
><br>
><br>
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><br>
<br>
<br>
<br>
--<br>
Professor Laurence Marks<br>
Department of Materials Science and Engineering<br>
Northwestern University<br>
<a href="http://www.numis.northwestern.edu" target="_blank">www.numis.northwestern.edu</a> <a href="tel:1-847-491-3996" value="+18474913996">1-847-491-3996</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></div>