<div dir="ltr"><div>Thank you Sir. Kindly have a look at the collected data below so that you can understand my problem. This data is for a AB2C4 type spinel compound. Would you explain this unit cell energy trend ? Also as you can see band gap starts increasing slightly with the pressure after a certain limit. <br>
In volume optimization you get optimized volume. If you put that volume in Murnaghan equation of state with pressure (e.g, 10GPa) then you will get the repective new volume at 10GPa from which you can calculate respective lattice constant at 10 GPa (which can be used in optimization process to get structural data at 10 GPa). I hope this is correct way. May you carefully analyze the data to find where is the actual problem. <br>
<br></div>
<table class="" style="width:100%;border-collapse:collapse;border:medium none" border="1" cellpadding="0" cellspacing="0" width="100%">
<tbody><tr style="height:9.85pt">
<td style="width:16.66%;border-width:1pt medium;border-style:solid none;border-color:black -moz-use-text-color;background:none repeat scroll 0% 0% rgb(198,217,241);padding:0cm 5.4pt;height:9.85pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US">Pressure</span></b></p>
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US">GPa</span></b></p>
</td>
<td style="width:16.66%;border-width:1pt medium;border-style:solid none;border-color:black -moz-use-text-color;background:none repeat scroll 0% 0% rgb(198,217,241);padding:0cm 5.4pt;height:9.85pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif";letter-spacing:-0.05pt" lang="EN-US">V
(a.u)<sup>3</sup></span></b><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US"> with GGA</span></b></p>
</td>
<td style="width:16.66%;border-width:1pt medium;border-style:solid none;border-color:black -moz-use-text-color;background:none repeat scroll 0% 0% rgb(198,217,241);padding:0cm 5.4pt;height:9.85pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US">U(Internal free anion parameter)</span></b></p>
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US">with GGA</span></b></p>
</td>
<td style="width:16.66%;border-width:1pt medium;border-style:solid none;border-color:black -moz-use-text-color;background:none repeat scroll 0% 0% rgb(198,217,241);padding:0cm 5.4pt;height:9.85pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US">E<sub>0</sub></span></b></p>
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US">(Ry)</span></b></p>
</td>
<td style="width:16.66%;border-width:1pt medium;border-style:solid none;border-color:black -moz-use-text-color;background:none repeat scroll 0% 0% rgb(198,217,241);padding:0cm 5.4pt;height:9.85pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:normal" align="center"><b style><span style="font-size:10pt;font-family:"Times New Roman","serif"" lang="EN-US">E<sub>g </sub>with mBJ-GGA</span></b></p>
</td>
<td style="width:16.66%;border-width:1pt medium;border-style:solid none;border-color:black -moz-use-text-color;background:none repeat scroll 0% 0% rgb(198,217,241);padding:0cm 5.4pt;height:9.85pt" valign="top" width="16%">
<p class="" style="text-align:center;line-height:150%" align="center"><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">E<sub>g </sub>with </span></b><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">GGA+U</span></b></p>
</td>
</tr>
<tr style>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US"> </span></b></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif";letter-spacing:-0.05pt" lang="EN-US"> </span></b></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US"> </span></b></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US"> </span></b></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US"> </span></b></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><b style><span style="font-size:10pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US"> </span></b></p>
</td>
</tr>
<tr style>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">0</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">2099.381</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">0.2544<sup> </sup></span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">-60638.684</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">2.733</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">1.685</span></p>
</td>
</tr>
<tr style>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">10</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">1885.611</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">0.2529</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">-60638.686</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">2.696</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">1.835</span></p>
</td>
</tr>
<tr style>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">20</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">1752.858</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">0.2521</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">-60638.683</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">2.646</span></p>
</td>
<td style="width:16.66%;border:medium none;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">1.813</span></p>
</td>
</tr>
<tr style>
<td style="width:16.66%;border-width:medium medium 1pt;border-style:none none solid;border-color:-moz-use-text-color -moz-use-text-color black;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">30</span></p>
</td>
<td style="width:16.66%;border-width:medium medium 1pt;border-style:none none solid;border-color:-moz-use-text-color -moz-use-text-color black;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">1658.429</span></p>
</td>
<td style="width:16.66%;border-width:medium medium 1pt;border-style:none none solid;border-color:-moz-use-text-color -moz-use-text-color black;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">0.2515</span></p>
</td>
<td style="width:16.66%;border-width:medium medium 1pt;border-style:none none solid;border-color:-moz-use-text-color -moz-use-text-color black;padding:0cm 5.4pt" valign="top" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">-60638.678</span></p>
</td>
<td style="width:16.66%;border-width:medium medium 1pt;border-style:none none solid;border-color:-moz-use-text-color -moz-use-text-color black;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">2.598</span></p>
</td>
<td style="width:16.66%;border-width:medium medium 1pt;border-style:none none solid;border-color:-moz-use-text-color -moz-use-text-color black;padding:0cm 5.4pt" width="16%">
<p class="" style="margin-bottom:0.0001pt;text-align:center;line-height:150%" align="center"><span style="font-size:9pt;line-height:150%;font-family:"Times New Roman","serif"" lang="EN-US">1.789</span></p>
</td>
</tr>
</tbody></table>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Jun 21, 2013 at 5:37 PM, Stefaan Cottenier <span dir="ltr"><<a href="mailto:Stefaan.Cottenier@ugent.be" target="_blank">Stefaan.Cottenier@ugent.be</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I am studying pressure dependent study for the first time. On increasing<br>
pressure from 0 to 30 GPa with a step of 10GPa, I got almost same unit<br>
cell enrergy for 0, 10, 20, 30 GPa. Why it is same ? May anyone explain<br>
</blockquote>
<br>
What is your definition of 'almost'? In that pressure range, total energy will change (increase) by something as 5 mRy/atom. That may look small with respect to a total energy of several thousands of Ry, indeed.<br>
<br>
Moreover, how do you 'apply pressure with steps of 10 GPa' in wien2k? Reducing the lattice parameters is the only thing you can do. Are you sure you aren't looking at 4 identical calculations?<br>
<br>
Stefaan<br>
<br>
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