Hi;
I am actually using fermits to get electronic free energy, not as a
smearing method (see my initial email). We are doing high
pressure/temperature calculations (300 GPa and up to 7000 K). So, any
help on letting WIEN2k accept that?
Thanks;
Sabry
On 05/15/2018 03:34 AM, Peter Blaha wrote:
Thanks for the bug report in init_lapw.
Please note: when the temperature (broadening) is set to zero, it will
use automatically "room temperature" (0.0018 Ry).
On 05/15/2018 06:40 AM, Gavin Abo wrote:
I think you found a bug in init_lapw. The fix seems like it should
be simple though. On line 498 in the init_lapw script in the sed
command, it looks like $fermit just needs changed to $fermits.
I made a patch file called init_lapw.patch [
https://github.com/gsabo/WIEN2k-Patches/tree/master/17.1 ], which you
should be able to apply and try simply using:
username@computername:~/Desktop$ cd $WIENROOT
username@computername:~/WIEN2k$ wget
https://raw.githubusercontent.com/gsabo/WIEN2k-Patches/master/17.1/init_lapw.patch
username@computername:~/WIEN2k$ patch -b init_lapw init_lapw.patch
patching file init_lapw
Maybe F is the :ENE (TOTAL ENERGY) in case.scf.
I tried following what a previous user did [
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg10319.html
] but with a quick TiC calculation using run_lapw in WIEN2k 17.1:
T = 1000 K = 0.00633 Ry
init_lapw -b -fermits 0.00633
TiC.scf::ENE : ********** TOTAL ENERGY IN Ry = -1783.95041939
TiC.output2: Kb * T = 0.00633000
TiC.output2: -T*Entr = -0.00054181
T = 0 K = 0.0 Ry
init_lapw -b -fermits 0.0
TiC.scf::ENE : ********** TOTAL ENERGY IN Ry = -1783.94928338
TiC.output2: Kb * T = 0.00180000
TiC.output2: -T*Entr = -0.00005329
F_1000K - F_0K = (E - T*S) - (E - 0) = -T*S = -1783.95041939 -
(-1783.94928338) = -0.001136 => -T*S = -0.001136
If -T*S divided by 2:
-T*S = -0.001136/2 = - 0.000568 <- This seems reasonably close to the
above -0.00054181 for T = 1000 K.
As I recall, the -T*S term was doubled in WIEN2k versions after 2014
[
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg10319.html
].
Though, there may be a flaw in my above calculation.
On 5/14/2018 5:35 PM, Sabry Moustafa wrote:
Hi;
I am interested in the electronic free energy (F=E-TS) using the
finite temperature DFT using Fermi-Dirac statistics (i.e., Mermin's
extension to 0 K DFT) -- i.e., I am not just looking for Fermi-Dirac
as a broadening/smearing technique. So,how this can be done in WIEN2k?
It looks like I have to define "-fermits X" in the init_lapw command
(where X= kT, in Ry). But when I did (T=1000K in my case):
init_lapw -b -fermits 0.00633
I got "fermit: Undefined variable." at the end. This is fixed though
when defined fermit as well:
init_lapw -b -fermit 0.00633 -fermits 0.00633
So, do I have to define both?
Also, where can I find this "free energy F". It does not seem to be
the "TOTAL ENERGY" in case.scf. Seems like I need to add this "TOTAL
ENERGY" (E) to "-T*Entr" (-TS) in case.output2 file to get F?
Thanks ;
Sabry
:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:
Sabry G. Moustafa, Ph.D.
Department of Chemical and Biological Engineering,
University at Buffalo, The State University of New York.
511 Furnas Hall
Buffalo, NY 14260-4200
716-645-1186 (office)
716-239-8543 (cell)
E-mail: sabry...@buffalo.edu <mailto:sabry...@buffalo.edu>
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