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Dear Benjamin Smith,<br>
<br>
what do you mean with convergence graph? The total energy with
increasing cutoff?<br>
I thought that this does not tell you anything, but maybe I'm wrong.
You should look<br>
at changes in the electronic structure and geometry...<br>
<br>
Furthermore,<br>
1. if you want to calculate a molecule, why do you use more k points
than just Gamma?<br>
2. a box of a size of about 5 Angstrom might be too small (celldm is
in Bohr)<br>
<br>
I guess that the box size together with the two points above can
lead to a minimum in the<br>
total energy which has nothing to do with the molecule. Easy way to
test would be to<br>
increase the box.<br>
<br>
Regards<br>
<br>
Thomas<br>
<br>
<div class="moz-cite-prefix">On 09/15/2014 11:41 AM, Benjamin Smith
wrote:<br>
</div>
<blockquote
cite="mid:1410774066.2298.YahooMailNeo@web186005.mail.ir2.yahoo.com"
type="cite">
<div style="color:#000; background-color:#fff;
font-family:garamond, new york, times, serif;font-size:12pt">
<div>Hello,</div>
<div><br>
</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;">I have been running tests of PBE
pseudopotentials using an F2 molecule within a cubic box. For
pbe-n-kjpaw, pbe-n-rrkjus and both of their relativistic
equivalents, the convergence graph is very strange. There is
not a smooth decline in the graph, it actually dips to a
minimum around 35Ry, and does not satisfactorily converge
until around 70Ry. I have not seen a graph such as this for
convergence before, any advice would be appreciated.</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;"><br>
</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;">Here is my input:</div>
<br>
&control<br>
prefix='testf',<br>
pseudo_dir='/home/chemeng/Benjamin/ppots'<br>
outdir = '/home/chemeng/Benjamin/PVDF/test',<br>
/<br>
&system <br>
ibrav= 1, celldm(1) =10, nat=2, ntyp= 1,<br>
ecutwfc = 100 ,<br>
/<br>
&electrons<br>
/<br>
/<br>
ATOMIC_SPECIES<br>
F 18.998 F.pbe-n-rrkjus_psl.0.1.UPF<br>
ATOMIC_POSITIONS (crystal)<br>
F 0.000000000 0.00000000 0.000000000<br>
F 0.0 0.0 0.268<br>
K_POINTS automatic<br>
4 4 4 0 0 0<br>
<br>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;"><br>
</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;">Thanks.</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;"><br>
</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;">Benjamin Smith</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;">Visiting Researcher</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;">Chemical and Process Eng.</div>
<div style="color: rgb(0, 0, 0); font-size: 16px; font-family:
garamond,new york,times,serif; background-color: transparent;
font-style: normal;">Uni. of Strathclyde</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Dr. rer. nat. Thomas Brumme
Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie
Sorbonne Universités - UPMC Univ Paris 06
4 Place Jussieu
75005 Paris
Tel: +33 (0) 1 442 77204
email: <a class="moz-txt-link-abbreviated" href="mailto:Thomas.Brumme@impmc.upmc.fr">Thomas.Brumme@impmc.upmc.fr</a></pre>
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