Dear Mohaddeseh,
please note that few bugs have been recently fixed in epsilon.x with QE release
5.4.0. If you have been using any other version of QE you may want to give a
try to this latest release
reading from the logs
------------------------------------------------------------------------
r12218 | giannozz | 2016-03-15 18:17:56 +0100 (mar, 15 mar 2016) | 2 lines
Incorrect sum over pools in LSDA case (courtesy of Mariella Ippolito, CINECA)
------------------------------------------------------------------------
r12082 | ferretti | 2016-01-30 10:19:26 +0100 (sab, 30 gen 2016) | 11 lines
Contributions from Tae Yun Kim and Cheol-Hwan Park (Seoul National University)
Fixed in epsilon.f90:
* Intraband contribution of nspin=2 was twice as much as that of nspin=1.
* epsr(w --> infinity) went to 2 in nspin=2.
* It was assumed that electronic occupations are in the range of 0-2 for
nspin=2 (0-1 for nspin=1).
But with 'mp' and 'mv' smearing this is not true, and can give ~8 %
underestimation of epsi
in the case of sodium metal.
* Instead of directly calculating the derivative of Fermi Dirac occupation,
now we use w0gauss function which is already in the QE modules.
------------------------------------------------------------------------
Some more precise info about the code can be found here:
~/espresso-5.4.0/PP/Doc/eps_man.tex
As a general point, if you have any dubts that your calculations are not
working properly you should be more specific (this input generates this output
which eg shows these problems)... asking whether a code is expected to provide
correct results is not very effective
concerning the comparison of epsilon.x with ph.x (or linear response in
general), one needs to be careful about the physical content of the
calculations:
* DFT linear response as implemented in QE can compute the (static)
response of a system of interacting electrons treated within a given
XC-functional (let's consider ions clamped for the moment)
* epsilon.x computes the independent particle response (both static and
dynamic) of a Kohn-Sham system (neglecting both local fields and fxc
contributions)
* epsilon.x does not take the non-locality of the pseudopot into account
(it works as if p were the physical momentum of the electrons)
hope it helps
Andrea
Regarding epsilon.x code in QE, I was wondering to know whether it will lead
to logical results?
Is it possible to compare the static dielectric constant obtained by
epsilon.x code with that of ph.x code?
I was wondering if you would introduce me the paper which has used
postprocessing code (epsilon.x).
Thanks in advance for your help!
Regards,
Mohaddeseh
--
---------------------------------------------------------
Mohaddeseh Abbasnejad,
Room No. 323, Department of Physics,
University of Tehran, North Karegar Ave.,
Tehran, P.O. Box: 14395-547- IRAN
Tel. No.: +98 21 6111 8634 & Fax No.: +98 21 8800 4781
Cellphone: +98 917 731 7514
E-Mail: [email protected]
Website: http://physics.ut.ac.ir
---------------------------------------------------------
--
Andrea Ferretti, PhD
S3 Center, Istituto Nanoscienze, CNR
via Campi 213/A, 41125, Modena, Italy
Tel: +39 059 2055322; Skype: andrea_ferretti
URL: http://www.nano.cnr.it
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