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<div class="moz-cite-prefix">Not sure if it helps, but below are
notes I have made on the electric field:<br>
--------------------------------------------------------------------------------------------<br>
Use of the electric field seems somewhat undocumented.<br>
<br>
Reference the case.in0 section (7.1.3) in the WIEN2k usersguide [
<a class="moz-txt-link-freetext" href="http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf">http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf</a> ].<br>
<br>
There seems to be 13 modes and 2 Fourier options to choose from.
To list the modes, add: <br>
<br>
-999 2<br>
<br>
on line 4 in the case.in0 file, then run in a terminal in the case
directory:<br>
<br>
x lapw0<br>
<br>
It should output:<br>
<br>
Available E-field modes<br>
Mode 0 is Analytic triangular
ramp <br>
Mode 1 is =0 if |z|<lambda, otherwise
E*cos((z0-lambda)*pi2/(0.5-lambda)) <br>
Mode 2 is =0 if |Z|<lambda, otherwise
E*(1.D0-cos((z0-lambda)*pi2/(0.5-lambda))) <br>
Mode 3 is =0 if |z|<lambda, otherwise
E*(1-cos((z0-lambda)*pi/(0.5-lambda)))*0.5D0 <br>
Mode 4 is =E if |z|<lambda, otherwise
E*(0.5D0-Z0)/(0.5d0-lambda) <br>
Mode 5 is =0 if |z|<lambda, otherwise
E*(1.D0-(0.5D0-Z0)/(0.5d0-lambda)) <br>
Mode 6 is Form from Lozovoi et al, J. Chem Phys, 115, 1661, 2001,
normalized to max of 1 <br>
Mode 7 is Form from Lozovoi et al, J. Chem Phys, 115, 1661,
2001 <br>
Mode 8 is =Constant
E
<br>
Mode 9 is =0 if |z|<lambda, otherwise
E <br>
Mode 10 is =E if |z|<lambda, otherwise
E*((1-cos((z0-lambda)*pit/cut))*0.5D0) <br>
Mode 11 is Numerical Triangular ramp from E/2 to
-E/2 <br>
Mode 12 is Numerical Triangular ramp from 0 to
-E <br>
Add 20 for finite Fourier series<br>
Add 40 for Fourier expansion within RMTs<br>
<br>
Note: The above list isn't fully displayed when x lapw0 is ran in
w2web, so use a terminal instead of w2web.<br>
<br>
According to the post<br>
<br>
<a class="moz-txt-link-freetext" href="http://zeus.theochem.tuwien.ac.at/pipermail/wien/2008-May/010928.html">http://zeus.theochem.tuwien.ac.at/pipermail/wien/2008-May/010928.html</a><br>
<br>
run a typically scf cycle to convergence without the electric
field (line 4 blank in case.in0).<br>
<br>
Then, add the electric field. For example, if "Mode 8 is
=Constant E" is chosen with an amplitude of 5 Ry, then line 4 of
case.in0 would be<br>
<br>
8000 5<br>
<br>
where Mode = IEFIELD/1000 = 8000/1000 = 8<br>
<br>
If a value of lambda of say 3 is specified such as for Mode 1,
then add it as a third column value to line 4 of case.in0:<br>
<br>
1000 5 3<br>
<br>
Then, run x lapw0 or another scf cycle for the electric field.<br>
<br>
I don't know if a supercell needs to be used for all or just some
of the potentials. Could try asking the mailing list. Also,
refer to the posts:<br>
<br>
<a class="moz-txt-link-freetext" href="http://zeus.theochem.tuwien.ac.at/pipermail/wien/2011-June/014946.html">http://zeus.theochem.tuwien.ac.at/pipermail/wien/2011-June/014946.html</a><br>
<a class="moz-txt-link-freetext" href="http://zeus.theochem.tuwien.ac.at/pipermail/wien/2004-September/003549.html">http://zeus.theochem.tuwien.ac.at/pipermail/wien/2004-September/003549.html</a><br>
<a class="moz-txt-link-freetext" href="http://zeus.theochem.tuwien.ac.at/pipermail/wien/2008-September/011449.html">http://zeus.theochem.tuwien.ac.at/pipermail/wien/2008-September/011449.html</a><br>
<a class="moz-txt-link-freetext" href="http://zeus.theochem.tuwien.ac.at/pipermail/wien/2008-September/011340.html">http://zeus.theochem.tuwien.ac.at/pipermail/wien/2008-September/011340.html</a><br>
<br>
E-field source code: SRC_lapw0/epot1.f<br>
--------------------------------------------------------------------------------------------<br>
<br>
As a quick test only, I put "120 -0.50" in line 4 of TiC.in0 and
ran x lapw0. The output in TiC.scf0 suggests the 120 gives a
triangular ramp electric field with 120 Fourier coefficients, and
it also sets an amplitude of -0.5 Ry. So I'm wondering if the
behavior seen in the difference observed between structures A
& B has anything to due with how the triangular ramps have
been positioned in those two structures.<br>
<br>
username@computername:~/wiendata/TiC$ grep :EFIELD *.scf0<br>
:EFIELD E-field of -0.50000 Ry with 120 Fourier
coefficients requested<br>
:EFIELD Form is Analytic triangular
ramp <br>
:EFIELD Number of FC in E-field 8 , Largest 14<br>
<br>
On 3/7/2017 8:59 AM, Laurence Marks wrote:<br>
</div>
<blockquote
cite="mid:CANkSMZAaNY1P1D6DJQErAV_oFPtZNgy95f3Q=95HJmYQr2_anw@mail.gmail.com"
type="cite">
<div dir="ltr">I probably should know/remember the answer to this
question, but I don't.
<div><br>
</div>
<div>In lapw0 we can add an electric field, is the energy right
or not? </div>
<div><br>
</div>
<div>For reference, I have two different structures A & B
and I want to compare the change in energy between the two in
a field. The difference is opposite to what I expected, so
either my expectation is wrong or an energy term is missing.
For reference, I have added "120 -0.50" at the bottom of
case.in0 and I am minimizing the positions/forces (which I
seem to remember were right but that does not prove that a
constant is not missing). Uncharged unit cell.</div>
<div><br>
<div><br>
</div>
-- <br>
<div class="gmail_signature">
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<div dir="ltr"><span
style="font-size:12.8px">Professor
Laurence Marks</span><br>
</div>
<div dir="ltr"><span
style="font-size:12.8px">"Research is to
see what everybody else has seen, and to
think what nobody else has thought", </span><span
style="font-size:12.8px">Albert
Szent-Gyorgi</span><br>
<a moz-do-not-send="true"
href="http://www.numis.northwestern.edu"
target="_blank">www.numis.northwestern.edu</a> ; <span
style="font-size:12.8px">Corrosion in
4D: </span><a moz-do-not-send="true"
href="http://MURI4D.numis.northwestern.edu"
style="font-size:12.8px" target="_blank">MURI4D.numis.northwestern.edu</a>
<div><span style="font-size:12.8px">Partner
of the CFW 100% program for gender
equity, </span><a
moz-do-not-send="true"
href="http://www.cfw.org/100-percent"
style="font-size:12.8px"
target="_blank">www.cfw.org/100-percent</a></div>
<div>Co-Editor, Acta Cryst A</div>
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