<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">I don't know the details of r.x code
but I think that, physically, what matters is the two atoms are
crystallographically equivalent or not .therefore I think space
group symmetry is the relevant one.<br>
<br>
stefano<br>
<br>
On 07/10/2012 05:54 AM, Peng Chen wrote:<br>
</div>
<blockquote
cite="mid:CAP_5U0cVAHQYUfpX_t_13ws=cqzwVKE+232zx_Tf0yRorcmZgQ@mail.gmail.com"
type="cite">
<pre wrap="">Dear All,
In the calculation of U, how can we determine the equivalence of the ions,
by site symmetry or space group symmetry?
E.g ABO3, B ions has 2 different site symmetries (B(1) B(2)). Shall we run
calculation on perturbing B(1) and B(2) ions or just a B ion?
In order to find U in B ions, I tried to run calculation with perturbing
just on B, and r.x gave some errors that it needs to read more data.
So I guess it needs the perturbed data from other atoms. Shall I use the
procedures listed below?
1. run scf calculation with Hubbard_U(i)= 1.d-20
2. run scf with perturbing on an A ion
3. run scf with perturbing on a B(1) ion
4. run scf with perturbing on a B(2) ion
5. run scf with perturbing on an O ion
</pre>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Pw_forum mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a>
<a class="moz-txt-link-freetext" href="http://www.democritos.it/mailman/listinfo/pw_forum">http://www.democritos.it/mailman/listinfo/pw_forum</a>
</pre>
</blockquote>
<br>
<br>
</body>
</html>