Dear PWSCF community<br>
<br>
In my study I got a problem which I can't solve by myself,<br>
unfortunately. I hope you can give me some tips where I made a<br>
mistake. I have to to investigate the energy difference between<br>
graphite and diamond, but I can't get trusted result.First of all, I<br>
used LDA PP (PZ), I tested it by subsequently increasing of energy<br>
cutoff (from 30 Ry to 120 Ry) as well as increasing of k-points mesh<br>
(4x4x1 for graphite, 4x4x4 for diamond; 6x6x2 for graphite, 6x6x6 for diamond;<br>8x8x3 for graphite, 8x8x8 for diamond; 10x10x4 for graphite, 10x10x10 for diamond).<br>I got the difference
between energies of diamond and graphite and tried to understand it<br>
trend (please, see attached figure). As you can see from the figure<br>
difference between energy diamond and graphite is almost zero so I<br>
can't say with confidence what structure is more favorable.<br>
This result different from other theoretical and experimental<br>
studies, therefore it seems that I did something wrong...<br>
<br>
My result: ~ 0.001±0.001 eV/atom<br>
<br>
_______________________________________________<div id=":sp"><br>
| Energy difference (eV/atom) | Method | Reference |<br>
| 0.03 |Experiment | PRB29_6996 |<br>
| 0.01 | LDA-PP | PRB29_6996 |<br>
| 0.04 | LDA-PP | PRB54_14994|<br>
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Input files for diamond and graphite are attached to the letter.</div><br clear="all"><br>-- <br><div><font face="arial,helvetica,sans-serif">Sincerely yours</font></div><div><b><font face="arial,helvetica,sans-serif">Alexander G. Kvashnin</font></b></div>
<div><font face="arial,helvetica,sans-serif">--------------------------------------------------------------------------------------------------------------------------------</font></div><div><font face="arial,helvetica,sans-serif">First year of master degree study</font></div>
<div><font face="arial,helvetica,sans-serif">Moscow Institute of Physics and Technology </font><a href="http://mipt.ru/" target="_blank"><font face="arial,helvetica,sans-serif">http://mipt.ru/</font></a></div><div>
<font face="arial,helvetica,sans-serif">141700, Institutsky lane 9, Dolgoprudny, Moscow Region, Russia</font><font face="arial,helvetica,sans-serif"><br></font></div><div><font face="arial,helvetica,sans-serif"><br></font></div>
<div><font face="arial,helvetica,sans-serif">Junior research scientist</font><font face="arial,helvetica,sans-serif"><br></font></div><div><font face="arial,helvetica,sans-serif">Technological Institute for Superhard </font></div>
<div><font face="arial,helvetica,sans-serif">and Novel Carbon Materials </font><a href="http://www.ntcstm.troitsk.ru/" target="_blank"><font face="arial,helvetica,sans-serif">http://www.ntcstm.troitsk.ru/</font></a></div>
<div><font face="arial,helvetica,sans-serif">142190, Central'naya St. 7a, Troitsk, Moscow Region, Russia</font></div><div><font face="arial,helvetica,sans-serif">================================================================</font></div>
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