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<p>Dear Dr. HOUARI,<br>
<br>
Thank you for your reply. I did not correct the band gap in any
system. I am hoping if I apply some U parameter to Zn-3d, Co-3d
and maybe to S-3p, I can capture the physics better. In this
pursuit, some V parameter might also be an option. But this is not
the problem I am facing. I am facing problem on how to obtain
these U and V values. For undoped, periodic system, we can get the
value using hp.x with simple unit cell. But the problem is for
aperiodic doped system like the one I have. <br>
<br>
As you said, the calculated U from the 8 atoms ZnS unit cell is
probably okay to use for 64 atoms supercell. But if I dope the
unit cell (to get the U value of Co), this system (25% doping) is
much different than the 64 atoms supercell (3.125% doping). And
when I am trying to run hp.x directly for the 64 atoms (U applied
only to the single Co), only a single iteration of 1 q point takes
an hour using 2240 CPUs. So, it would take weeks to complete a
calculation! <br>
<br>
I am hoping maybe I can calculate the U parameter separately for
Co unit cell (i.e., Co-HCP) and then maybe for Zn and S from ZnS
unit cell. But I have no rationale to support that it should work.
And also the inter-site parameters cannot be obtained following
this. <br>
<br>
Sincerely,<br>
Abdul<br>
</p>
<div class="moz-cite-prefix">On 5/21/2024 7:03 PM, Abdesalem Houari
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1411808389.900741.1716307381255@mail.yahoo.com">
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<div dir="ltr" data-setdir="false"><font size="1">Dear Abdul
Muhaymen,</font></div>
<div dir="ltr" data-setdir="false"><font size="1"><br>
</font></div>
<div dir="ltr" data-setdir="false"><font size="1">You say that
your results are fine, except the band gap ! How did you
correct it in pure ZnS, before Co-doping ? <br>
</font></div>
<div dir="ltr" data-setdir="false"><font size="1">The most
commun way in DFT is hybrid functionals (like HSE 06),
which obviously are very demanding in computational cost.
So the DFT+U (+V) could be a nice alternative. Here I
think you might need on-site U not only for Co, but also
for Zn (and as you said may be S). Since ZnS is a band
insulator and covalent compound, the inter-site V could
play an important role.</font></div>
<div dir="ltr" data-setdir="false"><font size="1"><br>
</font></div>
<div dir="ltr" data-setdir="false"><font size="1">In principle
U and V <span><font style="background-color: inherit;"
size="1">parameters are neither transferable nor
universal</font></span>, but in your case ( calculated
U from 8 atoms unit cell to use in 64 atoms supercell), I<span><font
style="background-color: inherit;" size="1"> guess </font></span>it
should be OK !<br>
</font></div>
<div dir="ltr" data-setdir="false"><font size="1"><br>
</font></div>
<div dir="ltr" data-setdir="false"><font size="1">Best regards<br>
</font></div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false"> <br>
</div>
<div><br>
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<div
style="text-align:left;font-family:sans-serif;font-size:13px;" dir="ltr"
data-setdir="false"><font
style="font-family:lucida console, sans-serif;" size="2">=============================</font><font
size="2">========<br
style="font-family:lucida console, sans-serif;">
</font>
<div><font size="2"><font
style="font-family:lucida console, sans-serif;">Dr.
Abdesalem HOUARI</font></font></div>
<font size="2"><font
style="font-family:lucida console, sans-serif;">-------------------------------------------------------------------------------------------</font><br
style="font-family:lucida console, sans-serif;">
<font style="font-family:lucida console, sans-serif;">Department
of physics, Theoretical Physics Laboratory</font><br
style="font-family:lucida console, sans-serif;">
<font style="font-family:lucida console, sans-serif;"><a
moz-do-not-send="true">University of Bejaia</a>-06000.
Algeria</font><font
style="font-family:lucida console, sans-serif;">.</font><br
style="font-family:lucida console, sans-serif;">
<font style="font-family:lucida console, sans-serif;">E-mail: <span
style="text-decoration-line: underline; text-decoration-style: solid; text-decoration-color: currentcolor;"><a
moz-do-not-send="true">abdeslam.houari@univ-bejaia.dz</a></span>
& <a moz-do-not-send="true">habdslam@yahoo.fr</a></font><br
style="font-family:lucida console, sans-serif;">
<font style="font-family:lucida console, sans-serif;"><span
style="text-decoration-line: underline; text-decoration-style: solid; text-decoration-color: currentcolor; background-color: rgb(0, 0, 255); font-style: italic;"></span></font><a
style="font-family:lucida console, sans-serif;"
href="https://sites.google.com/site/houariabdeslam/homepage"
rel="nofollow" target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">https://sites.google.com/site/houariabdeslam/homepage</a><br
style="font-family:lucida console, sans-serif;">
<font style="font-family:lucida console, sans-serif;">===================================</font><span
style="font-family:lucida console, sans-serif;"></span></font><br>
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<div> On Tuesday, 21 May 2024 at 04:17:30 am GMT+1, Abdul
Muhaymin via users <a class="moz-txt-link-rfc2396E" href="mailto:users@lists.quantum-espresso.org"><users@lists.quantum-espresso.org></a>
wrote: </div>
<div><br>
</div>
<div><br>
</div>
<div>
<div dir="ltr">Hello all,<br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr">I am investigating single TM dopant in wide
band gap semiconductors such <br>
</div>
<div dir="ltr">as Co in ZnS. I am using a 64 atoms supercell
where I replaced one of <br>
</div>
<div dir="ltr">the Zn atom with a Co atom. I tested several
convergence with respect to <br>
</div>
<div dir="ltr">the supercell size. My results seem fine
except the band gap. Now I want <br>
</div>
<div dir="ltr">to apply the U correction to that Co-3d (and
maybe to S-2p). For this, <br>
</div>
<div dir="ltr">is it possible to use the unit cell (8 atoms)
and run hp.x to get the U <br>
</div>
<div dir="ltr">values? Or do I have to run hp.x with the
large supercell (2*2*2 unit <br>
</div>
<div dir="ltr">cell=64 atoms)?<br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr">Also, at the beginning of our studies, during
the structural relaxation <br>
</div>
<div dir="ltr">phase, we first found our lattice parameter
for the host semiconductor <br>
</div>
<div dir="ltr">from multiple scf calculations and
subsequently running an eos analysis <br>
</div>
<div dir="ltr">(ev.x). Then we ran relax calculation but not
vc-relax. We keep this <br>
</div>
<div dir="ltr">lattice parameter constant and when
introducing new dopants, we only <br>
</div>
<div dir="ltr">vary the atomic positions
(calculation='relax'). In this case, when <br>
</div>
<div dir="ltr">running hp.x, could we replace the vc-relax
calculation with relax <br>
</div>
<div dir="ltr">calculation to self-consistently get the U
values?<br>
</div>
<div dir="ltr"><br>
</div>
<div dir="ltr">Thanks,<br>
</div>
<div dir="ltr">Abdul Muhaymin<br>
</div>
<div dir="ltr">Graduate (MS) student, Materials Science and
Nanotechnology<br>
</div>
<div dir="ltr">Bilkent University, Ankara.<br>
</div>
<div dir="ltr"><br>
</div>
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