<html><body><div style="color:#000; background-color:#fff; font-family:garamond, new york, times, serif;font-size:12pt"><div><span>Dear Mr. Jose,<br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: "Garamond"; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: "Garamond"; background-color: transparent; font-style: normal;"><span>Thanks for your detail explanation. I'll try to use hybrid function as you suggest. I'll update the results asap.<br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: "Garamond"; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: "Garamond"; background-color: transparent; font-style: normal;"><span>Sincerely yours,<br></span></div><div style="color: rgb(0, 0, 0);
font-size: 16px; font-family: "Garamond"; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: "Garamond"; background-color: transparent; font-style: normal;"><span>Iwan D.<br></span></div><div> </div><div style="color:rgb(0, 0, 0);font-size:13px;background-color:transparent;font-style:normal;"><span><font face="lucida console, sans-serif"><font size="2"><b>***<br></b></font></font></span></div><div style="color:rgb(0, 0, 0);font-size:13px;background-color:transparent;font-style:normal;"><span><font face="lucida console, sans-serif"><font size="2"><b>Iwan Darmadi</b></font></font></span><br><span><font face="lucida console, sans-serif"> Undergrad.Student - Department of Physics</font></span><font face="lucida console, sans-serif"><br></font></div><div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;"><span><font face="lucida console, sans-serif"> Universitas Indonesia</font></span></div><div style="color:rgb(0, 0, 0);font-size:13px;background-color:transparent;font-style:normal;" class="yui_3_2_0_2_1344683897969181"><a rel="nofollow" target="_blank" href="http://www.iwandarmadi.wordpress.com/"><b></b></a><br></div> <div style="font-size: 12pt; font-family: "garamond", "new york", "times", serif;"> <div style="font-size: 12pt; font-family: "times new roman", "new york", "times", serif;"> <div dir="ltr"> <font size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> ""José C. Conesa"" <jcconesa@icp.csic.es><br> <b><span style="font-weight: bold;">To:</span></b> Iwan Darmadi <iwan_darmadi@rocketmail.com> <br><b><span style="font-weight: bold;">Cc:</span></b> PWSCF Forum
<pw_forum@pwscf.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Friday, January 25, 2013 6:31 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [Pw_forum] Fail to predict semiconductor<br> </font> </div> <br>
<div id="yiv1185301972">
<div>
Dear Iwan,<br>
In the paper you quote, the Ti:ZnO case has the Ti levels inside the
ZnO conduction band (see fig. 2) - and this even though the latter
band has been pushed up by applying an ad hoc shift to the Zn 4s
levels, so that the correct gap of ZnO is obtained. Thus it does not
seem that the calculation reported there predicts this system to be
a semiconductor. Of course, experimentally it may happen that the
material prepared, especially if it was made in even mildly
oxidizing environment, contains cation vacancies, possibly located
close to the Ti atoms (assuming these to be at tetrahedral sites -
which is not a preferred coordination for Ti) so that it could
behave as semiconductor.<br>
In any case computing correctly band gaps and level positions in
these systems is tricky even with post-DFT treatments. I try to
avoid if possible DFT+U (treating differently different electrons is
not very elegant), and to use hybrids instead. One problem with the
latter is that the fraction of Fock exchange to be used can be
questioned. Indeed one same fraction is not valid for both TiO2 and
ZnO. You can approach the situation better if that fraction is tuned
to the dielectric constant of the material. If you are interested in
this specific issue I invite you to look at my recent papers
<span style="font-size:11.0pt;
" lang="EN-US">J. Phys. </span><span style="font-size:11.0pt;
">Chem. C</span><span style="font-size:11.0pt;
"> 116 (2012) 18884</span>
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and Catal. Today in press (doi:
<span style="font-size:11.0pt;
color:black;" lang="EN-US">10.1016/j.cattod.2012.08.039)</span>
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</style> where this solution is explained better, although its
suitability for possibly metallic systems like yours can be
questioned as well.<br>
Regards,<br>
José-Carlos<br>
<br>
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<div class="yiv1185301972moz-cite-prefix">El 23/01/2013 15:56, Iwan Darmadi
escribió:<br>
</div>
<blockquote type="cite">
<div style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); font-size: 12pt; font-family: "garamond", "new york", "times", serif;">
<div id="yiv1185301972">
<div>
<div style="color:rgb(0, 0, 0);background-color:rgb(255,
255, 255);font-size:12pt;
">
<div id="yiv1185301972">
<div>
<div style="color:rgb(0, 0, 0);
background-color:rgb(255, 255, 255);font-size:12pt;
" class="yiv1185301972yui_3_7_2_15_1358952486394_49">
<div id="yiv1185301972yui_3_7_2_16_1358929912581_49"> Dear
Mr.Jose,</div>
<div><br>
</div>
<div id="yiv1185301972yui_3_7_2_16_1358929912581_122">Yes,
I do. But, as far as I know, transition metal
doped zno is semiconductor even theoretically
(according for example PRB 79/165202 and ). So I
assumed that without cation vacancy, Ti doped ZnO
might be semiconductor also.</div>
<div><br>
</div>
<div>Regards,</div>
<div>ID</div>
<div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_16_1358929912581_53"><span><font face="lucida console, sans-serif"><font size="2"><b>***<br>
</b></font></font></span></div>
<div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_16_1358929912581_55"><span><font face="lucida console, sans-serif"><font size="2"><b>Iwan Darmadi</b></font></font></span><br>
<span><font face="lucida console, sans-serif"> Undergrad.Student
- Department of Physics</font></span><font face="lucida console, sans-serif"><br>
</font></div>
<div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_16_1358929912581_57"><span><font face="lucida console, sans-serif"> Universitas
Indonesia</font></span></div>
<div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;" class="yiv1185301972yui_3_2_0_2_1344683897969181" id="yiv1185301972yui_3_7_2_16_1358929912581_59"><br id="yiv1185301972yui_3_7_2_16_1358929912581_61">
</div>
<div style="font-size: 12pt; font-family: "garamond", "new york", "times", serif;" id="yiv1185301972yui_3_7_2_16_1358929912581_64" class="yiv1185301972yui_3_7_2_16_1358929912581_63
yiv1185301972yui_3_7_2_15_1358952486394_59">
<div style="font-size:12pt;
" class="yiv1185301972yui_3_7_2_16_1358929912581_72
yiv1185301972yui_3_7_2_15_1358952486394_60">
<div dir="ltr"> <font face="Arial" size="2">
<hr size="1"> <b><span style="font-weight:bold;" id="yiv1185301972yui_3_7_2_16_1358929912581_116">From:</span></b>
Jose C. Conesa <a rel="nofollow" class="yiv1185301972moz-txt-link-rfc2396E" ymailto="mailto:jcconesa@icp.csic.es" target="_blank" href="mailto:jcconesa@icp.csic.es"><jcconesa@icp.csic.es></a><br>
<b><span style="font-weight:bold;">To:</span></b>
Iwan Darmadi
<a rel="nofollow" class="yiv1185301972moz-txt-link-rfc2396E" ymailto="mailto:iwan_darmadi@rocketmail.com" target="_blank" href="mailto:iwan_darmadi@rocketmail.com"><iwan_darmadi@rocketmail.com></a>; PWSCF
Forum <a rel="nofollow" class="yiv1185301972moz-txt-link-rfc2396E" ymailto="mailto:pw_forum@pwscf.org" target="_blank" href="mailto:pw_forum@pwscf.org"><pw_forum@pwscf.org></a> <br>
<b><span style="font-weight:bold;">Sent:</span></b>
Wednesday, January 23, 2013 3:09 PM<br>
<b><span style="font-weight:bold;">Subject:</span></b>
Re: [Pw_forum] Fail to predict semiconductor<br>
</font> </div>
<br>
<div id="yiv1185301972">
<div>
<div class="yiv1185301972moz-cite-prefix">Dear
Iwan,<br>
Do you know whether the experimentally
known Ti doped ZnO contains cation
vacancies?<br>
Good luck,<br>
José Carlos<br>
<br>
El 23/01/2013 6:50, Iwan Darmadi escribió:<br>
</div>
<blockquote type="cite">
<div style="color:rgb(0, 0, 0);background-color:rgb(255, 255, 255);font-size:12pt;
" class="yiv1185301972yui_3_7_2_16_1358929912581_78
yiv1185301972yui_3_7_2_15_1358952486394_66">
<div id="yiv1185301972">
<div>
<div style="color:rgb(0, 0,
0);background-color:rgb(255, 255,
255);font-size:12pt;">
<div id="yiv1185301972yui_3_7_2_15_1358917927192_49"><span id="yiv1185301972yui_3_7_2_15_1358917927192_73">Dear all,<br>
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_88"><span id="yiv1185301972yui_3_7_2_15_1358917927192_90"><br id="yiv1185301972yui_3_7_2_15_1358917927192_92">
</span></div>
<div id="yiv1185301972yui_3_7_2_15_1358917927192_83" style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;"><span id="yiv1185301972yui_3_7_2_15_1358917927192_81">I have calculated
electronic structure of Ti
doped ZnO in both GGA and
GGA+U scheme. Both scheme
predicts Ti doped ZnO is
metallic. In contrary, Ti
doped ZnO is well known as
semiconductor experimentally.
At first glance, I thought it
was local minimum problem of
DFT+U (like FeO problem in Mr.
Himmetoglu's tutorial). Then I
try to copy Mr. Himmetoglu's
trick to override a
"suspected" fully occupied
orbitals of Ti. Sadly, nothing
change, it's still a
metallic.</span><span id="yiv1185301972yui_3_7_2_15_1358917927192_112"><br id="yiv1185301972yui_3_7_2_15_1358917927192_121">
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_125"><span id="yiv1185301972yui_3_7_2_15_1358917927192_127"><br id="yiv1185301972yui_3_7_2_15_1358917927192_129">
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_119"><span id="yiv1185301972yui_3_7_2_15_1358917927192_117">Now,
I am confused whether this is
a really local minimum problem
or intrinsic limitation of DFT
it self.</span><span id="yiv1185301972yui_3_7_2_15_1358917927192_146"><br id="yiv1185301972yui_3_7_2_15_1358917927192_163">
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_167"><span id="yiv1185301972yui_3_7_2_15_1358917927192_169"><br id="yiv1185301972yui_3_7_2_15_1358917927192_171">
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_161"><span id="yiv1185301972yui_3_7_2_15_1358917927192_159">Do
anyone here have suggestions
so I can get semiconductor Ti
doped ZnO in the calculation ?<br>
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_140"><span id="yiv1185301972yui_3_7_2_15_1358917927192_142"><br id="yiv1185301972yui_3_7_2_15_1358917927192_144">
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_134"><span id="yiv1185301972yui_3_7_2_15_1358917927192_98">Ps.<br id="yiv1185301972yui_3_7_2_15_1358917927192_182">
</span></div>
<div style="color:rgb(0, 0,
0);font-size:16px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_180"><span id="yiv1185301972yui_3_7_2_15_1358917927192_178">I
have also attached my input
and output file.<br>
</span></div>
<div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_53"><span><font face="lucida
console, sans-serif"><font size="2"><b>***<br>
</b></font></font></span></div>
<div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_55"><span><font face="lucida
console, sans-serif"><font size="2"><b>Iwan Darmadi</b></font></font></span><br>
<span><font face="lucida
console, sans-serif"> Undergrad.Student
- Department of Physics</font></span><font face="lucida console,
sans-serif"><br>
</font></div>
<div style="color:rgb(0, 0,
0);font-size:13px;background-color:transparent;font-style:normal;" id="yiv1185301972yui_3_7_2_15_1358917927192_57"><span><font face="lucida
console, sans-serif"> Universitas
Indonesia</font></span><span class="yiv1185301972yui_3_2_0_2_1344683897969186" id="yiv1185301972yui_3_7_2_15_1358917927192_78"><br>
</span></div>
</div>
</div>
</div>
</div>
<br>
<br>
<pre>_______________________________________________
Pw_forum mailing list
<a rel="nofollow" class="yiv1185301972moz-txt-link-abbreviated" ymailto="mailto:Pw_forum@pwscf.org" target="_blank" href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a>
http://pwscf.org/mailman/listinfo/pw_forum</pre>
</blockquote>
<br>
<br>
<pre class="yiv1185301972moz-signature">--
José C. Conesa
Instituto de Catálisis y Petroleoquímica, CSIC
Marie Curie 2, Cantoblanco
28049 Madrid - Spain
Tel. +34-915854766</pre>
</div>
</div>
<br>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<br>
<pre class="yiv1185301972moz-signature">--
José C. Conesa
Instituto de Catálisis y Petroleoquímica, CSIC
Marie Curie 2, Cantoblanco
28049 Madrid - Spain
Tel. +34-915854766
</pre>
</div>
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