[Wien] Finite temperature DFT: electronic free energy

Thu May 17 23:56:16 CEST 2018

Converge first with a lower temperature (and relevant compression), do rm
*.bro* and increase the temperature in case.in2. Increase the upper energy
bound in case.in1 so it is at least 6 times |TS| above the T=0 Fermi energy
(you might need more).

And...check the literature to see if PBE or similar is valid at these
temperatures, it may be but I am not sure.

_____
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody
else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu

On Thu, May 17, 2018, 4:48 PM Sabry Moustafa <sabrygad at buffalo.edu> wrote:

> 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 $fermits.
> >>
> >> I made a patch file called init_lapw.patch [
> >>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_gsabo_WIEN2k-2DPatches_tree_master_17.1&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=Hn5eIySND1IkkC8SenMTlUEYgU3nny253vK7bDy-L0g&s=pchq-sckwiEtPKCc3NjC8McQxlngga41TZlRpVbB0x4&e=
> ], which you
> >> should be able to apply and try simply using:
> >>
> >> username at computername:~/Desktop$ cd $WIENROOT
> >> username at computername:~/WIEN2k$ wget
> >>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__raw.githubusercontent.com_gsabo_WIEN2k-2DPatches_master_17.1_init-5Flapw.patch&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=Hn5eIySND1IkkC8SenMTlUEYgU3nny253vK7bDy-L0g&s=6LnxjU7LcuE_qQ14bQf2bAVhfWK2JagDPwsg463SAcU&e=
> >> username at 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://urldefense.proofpoint.com/v2/url?u=https-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_msg10319.html&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=Hn5eIySND1IkkC8SenMTlUEYgU3nny253vK7bDy-L0g&s=-UMXEb4CU6-5g1bj24XAeH9V_U93yjUI01EDvqtB2pE&e=
> >> ] 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://urldefense.proofpoint.com/v2/url?u=https-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_msg10319.html&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=Hn5eIySND1IkkC8SenMTlUEYgU3nny253vK7bDy-L0g&s=-UMXEb4CU6-5g1bj24XAeH9V_U93yjUI01EDvqtB2pE&e=
> >> ].
> >>
> >> 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: sabrygad at buffalo.edu <mailto:sabrygad at buffalo.edu>
> >>
> >>
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> >>
> >
>
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