Dear Pashangpour,
what I meant is that the meaning of the variables intersmear and
intrasmear of epsilon is quite similar to that of degauss in DOS or
projwfc, and that convergences should be studied in a similar way...
(note that very often kpt meshes denser than those used for scf runs are
needed to converge DOS/projwfc/epsilon calculations)
Andrea
I mean inter and intera smearings in inputpp of epsilon calculation not in
inputscf. Do you mean I can set them similar
kpt, Ecuts and smearing in scf input?
Thanks
M Pashangpour
IIAU,Tehran,Iran
Sent from my iPhone
On 23 Nov 2016, at 19:56, Andrea Ferretti <[email protected]> wrote:
Dear Pashangpour,
the idea is very similar to the usual kpt convergence
vs smearing parameter for a DOS calculation.
At variance with scf runs, here you are computing a spectral quantity
(the dielectric function as a function of the frequency), meaning that you
may need a (much) finer mesh of kpts.
In general, the larger the smearing, the lower the resolution of your
spectrum (in the simplest case you are replacing dirac's deltas with
gaussians), while the larger the kpt mesh that you use, the smaller the
smearing parameter can be...
I would follow a recipe like this:
* set the smearing and converge the spectrum wrt kpts
* if the accuracy of the spectrum (ie the resolution of its features) is
ok with you, exit(),
otherwise reduce the smearing parameter and iterate
* by reducing the smearing you should expect to converge with a denser
mesh of kpts (a rule of thumb could be dk * delta ~ constant, where
dk is the kpt grid spacing and delta the smearing parameter.. though
it probably depends on the system and on your requirements)
Andrea
Dear all
How can I find suitable value of intersmear and intrasmear in
epsioln calculation via epsilon.x?
Thanks in advance
M. Pashangpour
PhD of physics
IAU,Tehran,Iran
Sent from my iPhone
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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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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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