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<p><font face="Times New Roman">In [1], it says:</font></p>
<p><font face="Times New Roman"><i>In Refs. [77,82] we showed that a
correct description of the band gap and electric-field
gradient (EFG) in Cu2O could only be achieved with the hybrid
functionals, while the results</i><i> </i><i>obtained with
the LDA, GGA, LDA+U, and mBJ methods</i><i> </i><i>were
qualitatively wrong.</i><br>
</font></p>
<p><font face="Times New Roman">In TABLE IV of [2], GGA (PBE) gap is
0.53 eV. In TABLE I of [3], mBJ gap is 0.82 eV.</font></p>
<p><font face="Times New Roman">I'm not seeing a WIEN2k value reported
for GGA+U, but maybe it is close to </font><font face="Times
New Roman"><font face="Times New Roman">the 0.79 eV gap (AMF, U
= 8 eV) LDA+U calculation [2] or </font>the 0.67 eV gap (with
U of 7 eV) GGA+U calculation by VASP [4].<br>
</font></p>
<p><font face="Times New Roman">The 0.53 eV, 0.82 eV, and 0.67 eV
above round up to be approximately 1.0 eV, which is around the
1.0 eV that you report.</font></p>
<p><font face="Times New Roman">On the other hand, GGA+U+mBJ
calculation may give </font><font face="Times New Roman"><font
face="Times New Roman">1.60 eV [6].</font></font></p>
<p><font face="Times New Roman">[1]
<a class="moz-txt-link-freetext" href="https://publik.tuwien.ac.at/files/PubDat_238321.pdf">https://publik.tuwien.ac.at/files/PubDat_238321.pdf</a></font><br>
</p>
[2] <a class="moz-txt-link-freetext" href="https://publik.tuwien.ac.at/files/PubDat_197400.pdf">https://publik.tuwien.ac.at/files/PubDat_197400.pdf</a><br>
<br>
[3] <a class="moz-txt-link-freetext" href="https://publik.tuwien.ac.at/files/PubDat_197196.pdf">https://publik.tuwien.ac.at/files/PubDat_197196.pdf</a><br>
<br>
[4] <a class="moz-txt-link-freetext" href="http://dx.doi.org/10.1063/1.3231869">http://dx.doi.org/10.1063/1.3231869</a><br>
<br>
[5] <a class="moz-txt-link-freetext" href="http://dx.doi.org/10.1063/1.4798706">http://dx.doi.org/10.1063/1.4798706</a> <br>
<br>
[6] <a class="moz-txt-link-freetext" href="http://dx.doi.org/10.1063/1.4798706">http://dx.doi.org/10.1063/1.4798706</a> (TABLE I)<br>
<br>
<div class="moz-cite-prefix">On 8/18/2017 9:14 PM, halim said wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1032135989.947308.1503112490218@mail.yahoo.com">
<div style="color:#000; background-color:#fff; font-family:times
new roman, new york, times, serif;font-size:13px">
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span
id="yui_3_16_0_ym19_1_1503112316742_2780">Dear Prof. Tran,</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span>Hi,</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span
id="yui_3_16_0_ym19_1_1503112316742_2901">Thank you for your
answer, I mean withing GGA, mBJ-GGA, and GGA+U, I found the
energy gap around 1 eV.</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span
id="yui_3_16_0_ym19_1_1503112316742_2902">In principle the
experimental gap is about 2 eV.</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span>Where is
the problem?</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span>Thank you
for your help.</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span>Yours
sincerely,</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span>Halim Said</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span><br>
</span></div>
<div id="yui_3_16_0_ym19_1_1503112316742_2781"><span>I a</span></div>
<div class="qtdSeparateBR"><br>
<br>
</div>
<div class="yahoo_quoted" style="display: block;">
<div style="font-family: times new roman, new york, times,
serif; font-size: 13px;">
<div style="font-family: HelveticaNeue, Helvetica Neue,
Helvetica, Arial, Lucida Grande, sans-serif; font-size:
16px;">
<div dir="ltr"><font size="2" face="Arial"> Le Vendredi 18
août 2017 23h29, <a class="moz-txt-link-rfc2396E" href="mailto:tran@theochem.tuwien.ac.at">"tran@theochem.tuwien.ac.at"</a>
<a class="moz-txt-link-rfc2396E" href="mailto:tran@theochem.tuwien.ac.at"><tran@theochem.tuwien.ac.at></a> a écrit :<br>
</font></div>
<br>
<br>
<div class="y_msg_container">
<div dir="ltr">Hi,<br clear="none">
<br clear="none">
What do you mean by 1 eV? Does it mean that all<br
clear="none">
gaps are at exactly 1.0 eV or in a range like 0.5-1.5
eV?<br clear="none">
<br clear="none">
You can compare your results with those in these two
articles:<br clear="none">
<a shape="rect"
href="https://publik.tuwien.ac.at/files/PubDat_197400.pdf"
target="_blank" moz-do-not-send="true">https://publik.tuwien.ac.at/files/PubDat_197400.pdf</a><br
clear="none">
<a shape="rect"
href="https://publik.tuwien.ac.at/files/PubDat_197196.pdf"
target="_blank" moz-do-not-send="true">https://publik.tuwien.ac.at/files/PubDat_197196.pdf</a><br
clear="none">
<br clear="none">
Cu2O is a special case for which mBJ and GGA+U are not
really<br clear="none">
better than GGA.<br clear="none">
<br clear="none">
FT<br clear="none">
<br clear="none">
On Friday 2017-08-18 21:42, halim said wrote:<br
clear="none">
<br clear="none">
>Date: Fri, 18 Aug 2017 21:42:24<br clear="none">
>From: halim said <<a shape="rect"
ymailto="mailto:halim_said04@yahoo.fr"
href="mailto:halim_said04@yahoo.fr"
moz-do-not-send="true">halim_said04@yahoo.fr</a>><br
clear="none">
>Reply-To: A Mailing list for WIEN2k users <<a
shape="rect"
ymailto="mailto:wien@zeus.theochem.tuwien.ac.at"
href="mailto:wien@zeus.theochem.tuwien.ac.at"
moz-do-not-send="true">wien@zeus.theochem.tuwien.ac.at</a>><br
clear="none">
>To: "<a shape="rect"
ymailto="mailto:wien@zeus.theochem.tuwien.ac.at"
href="mailto:wien@zeus.theochem.tuwien.ac.at"
moz-do-not-send="true">wien@zeus.theochem.tuwien.ac.at</a>"
<<a shape="rect"
ymailto="mailto:wien@zeus.theochem.tuwien.ac.at"
href="mailto:wien@zeus.theochem.tuwien.ac.at"
moz-do-not-send="true">wien@zeus.theochem.tuwien.ac.at</a>><br
clear="none">
>Subject: [Wien] problem of energy gap within mBJ
<div class="yqt8474273657" id="yqtfd06810"><br
clear="none">
><br clear="none">
>Dear Professor Peter Blaha, Tran and Wien2k
users,<br clear="none">
><br clear="none">
>I have computed the energy gap for Cu2O by using
GGA, mBJ, and GGA+U, I got same energy gap of 1 eV.<br
clear="none">
>In principle by using mBJ, the energy gap should
be increased close to expermimental value around 2
eV.<br clear="none">
>Why mBJ is giving same value as GGA and it is
not improved? even I tried GGA+U and the same
problem and no thing was changed for all
approximations.<br clear="none">
><br clear="none">
>I would be thankful for your suggestion and
answer to solve the problem.<br clear="none">
><br clear="none">
>Sincerely yours,<br clear="none">
><br clear="none">
>Halim Said</div>
<br clear="none">
</div>
</div>
</div>
</div>
</div>
</div>
</blockquote>
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