<div dir="ltr">Dear All,<div><br></div><div>Thank you for your replied all. It helps me a lot.</div><div>I usually only calculate magnetic properties, and it seems like that the relaxation does not affect the magnetic properties much (at least the material I calculate now).</div>
<div>I am wondering if the other properties are affected a lot more. Because two of my coworkers in another university told me that the relaxation must be performed for all calculations.</div><div>I am still not sure how to convince myself.</div>
<div>If the magnetic properties for relaxed structure is a little bit different from the magnetic properties for experimental (not relaxed) structure, what results should I believe?</div><div>Should I just believe the results that are close to experimental magnetic properties?</div>
<div>Then why the expert Dr. Novak did not do the relaxation? Is it because the relaxation for the known structures is really not needed?</div><div><br></div><div><br></div><div>All my best,</div><div>Jihoon Park</div></div>
<div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Jul 21, 2014 at 2:59 PM, Víctor Luaña <span dir="ltr"><<a href="mailto:victor@fluor.quimica.uniovi.es" target="_blank">victor@fluor.quimica.uniovi.es</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">On Mon, Jul 21, 2014 at 02:16:27PM -0500, Jihoon Park wrote:<br>
> I am wondering if we must do the relaxation for all calculations.<br>
> I have found some first principles studies with experimental lattice<br>
> constants, including Dr. Novak's work "PRB 71, 1844422 (2005)."<br>
> Therefore, I need to know if the first principles calculations with<br>
> experimental lattice constants are reliable or in what case, it is good<br>
> enough or somethings.<br>
> Could anybody please give me some guidance?<br>
<br>
</div></div>It depends very much on your intention. Optimizing an structure can be<br>
taken as a test of how appropriate is your calculation method for the<br>
system you are trying to analyze. The experimental value is the thing<br>
you are trying to reproduce, but not all experiments are done under<br>
the same precision, nor all experiments provide a well defined result.<br>
<br>
Remember that science is understanding, not only producing tables<br>
of numbers. Very simple models have been fundamental in science.<br>
For instance we owe our periodic table of the elements basically to<br>
ideas and concepts generated before quantum mechanics.<br>
<br>
It is not wrong, of course, the use a simple well defined recipe on a<br>
large collection of compounds trying to get some systematic rule.<br>
<br>
So, try to learn from the literature in your field and try to follow<br>
an unexploited road from the best starting point. Not a simple way but<br>
remember: It is easy to imagine a simple solution for a complex problem<br>
... the pity is that most are wrong!<br>
<br>
Best regards,<br>
Dr. Víctor Luaña<br>
<br>
--<br>
\|/a "After years of working on a problem the genius shout:<br>
|^.^| what an idiot I am ... the solution is trivial!'<br>
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! Dr.Víctor Luaña !<br>
! Departamento de Química Física y Analítica !<br>
! Universidad de Oviedo, 33006-Oviedo, Spain !<br>
! e-mail: <a href="mailto:victor@fluor.quimica.uniovi.es">victor@fluor.quimica.uniovi.es</a> !<br>
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