[Wien] optics broken symmetry
Peter Blaha
pblaha at theochem.tuwien.ac.at
Wed Sep 5 14:56:26 CEST 2018
This is an fcc lattice and shifts are breaking the symmetry and thus not
allowed.
In addition, the gap is at Gamma, so when you want epsilon at low
energies, you "need" Gamma.
PS: I've not tried other possible setups like R or B lattices or a P
supercell, but for the former symmetry will certainly be broken (you
cannot make a "cubic" k-mesh when using R or B lattices because of the
sqrt2 or 3 factors) and in the latter the computational effort will be
much larger anyway.
The optics with 200000k runs in 10 mins on a single core ....
On 09/05/2018 02:00 PM, Xavier Rocquefelte wrote:
> As you Laurence, I was thinking about the effect of shifting or not the
> kmesh!
>
> Peter, do you think it will lead to a better convergence?
>
> Cheers
>
> Xavier
>
>
> Le 03/09/2018 à 13:59, Laurence Marks a écrit :
>> What you are doing "should" work -- I have done similar things myself.
>> I have also managed to do it "not quite right" in the past as well.
>> The most obvious possibility is user error.
>>
>> One thing I would check is shifting the k-mesh. For reasons that I do
>> not fully understand this can break symmetry. A good thing to check is
>> no shift, this may solve the problem. You may want to test using TEMPS.
>>
>> You may also need to tighten the convergence. Breaking of symmetry can
>> be a very soft mode, and be only satisfied when one pushes to really
>> well converged results.
>>
>> On Sun, Sep 2, 2018 at 10:33 PM, Oleg Rubel <rubelo at mcmaster.ca
>> <mailto:rubelo at mcmaster.ca>> wrote:
>>
>> Dear Wien2k community,
>>
>> I try to compute opto-elastic properties of InP (zinc-blend
>> structure).
>> It is related to a change of the dielectric constant (real part) in
>> response to an applied strain. There are no problems with a
>> response to
>> a hydrostatic strain, and results agree well with experiments. A
>> problem
>> occurs with a uniaxial strain (strained along X-axis only by 0.05%).
>> Computed change in the dielectric constant is too large (~ an
>> order of
>> magnitude).
>>
>> Trying to trace back the problem, I did the following:
>> First, I initialize a tetragonaly-distorted zinc-blend structure
>> (init_lapw -b -vxc 19 -ecut -6.5 -numk 800) with the following
>> lattice
>> parameters
>>
>> F LATTICE,NONEQUIV.ATOMS: 2
>>
>> MODE OF CALC=RELA unit=ang
>>
>> 11.095785 11.090240 11.090240 90.000000 90.000000 90.000000
>>
>> Then I set the lattice parameters back to the cubic lattice
>>
>> F LATTICE,NONEQUIV.ATOMS: 2
>>
>> MODE OF CALC=RELA unit=ang
>>
>> 11.090240 11.090240 11.090240 90.000000 90.000000 90.000000
>>
>> and rerun (x dstart). This allows me to preserve the symmetry of a
>> distorted structure (see the structure file below).
>>
>> Next, I run SCF (run_lapw -ec 0.00001 -cc 0.0001) and optics with
>> 20x20x20 k-mesh. The results for Re and Im parts of the dielectric
>> constant are here:
>>
>> [oleg at feynman InP-w2k]$ head InP-w2k.epsilon
>> #
>>
>> # Lorentzian broadening with gamma= 0.100000 [eV]
>> # Im(epsilon) shifted by 0.7860 [eV]
>> # No intraband contributions added
>> #
>> # Energy [eV] Re_eps_xx Im_eps_xx Re_eps_yy Im_eps_yy
>> #
>> 0.013610 0.940850E+01 0.988634E-01 0.947674E+01 0.100908E+00
>> 0.040820 0.940928E+01 0.100340E+00 0.947756E+01 0.102453E+00
>> 0.068030 0.941084E+01 0.101855E+00 0.947919E+01 0.104042E+00
>>
>> It seems that the symmetry is broken, which causes later problems
>> with
>> opto-elastic coefficients as change of 0.07 in the second decimal
>> point
>> of Re_eps for such a small strain is too much.
>>
>> Once again, there are no problems when the strain tensor does not
>> break
>> the zinc-blend cubic symmetry.
>>
>> Any thoughts are highly appreciated.
>>
>>
>> Thank you in advance
>> Oleg
>>
>> --
>> Oleg Rubel (PhD, PEng)
>> Department of Materials Science and Engineering
>> McMaster University
>> JHE 359, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
>> Email: rubelo at mcmaster.ca <mailto:rubelo at mcmaster.ca>
>> Tel: +1-905-525-9140, ext. 24094
>> Web:
>> https://urldefense.proofpoint.com/v2/url?u=http-3A__olegrubel.mcmaster.ca&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=WpMS0L_jtI19kiPXo_QJrB9iBMQX1L9TeNePUM_x2Lw&s=YKfgMS8xLL_yM_B62Rds1s_GApfimaNcCR8kQSU2LLw&e=
>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__olegrubel.mcmaster.ca&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=WpMS0L_jtI19kiPXo_QJrB9iBMQX1L9TeNePUM_x2Lw&s=YKfgMS8xLL_yM_B62Rds1s_GApfimaNcCR8kQSU2LLw&e=>
>>
>> P.S. I run WIEN2k_16.1 (Release 11/17/2016). Our main cluster is down
>> for maintenance, so I was not able to check with the newest
>> version of
>> Wien2k.
>>
>> P.P.S. Here is the cubic structure file with a distorted symmetry
>> that I
>> run to get the data.
>>
>> InP
>>
>> F LATTICE,NONEQUIV.ATOMS: 2
>>
>> MODE OF CALC=RELA unit=ang
>>
>> 11.090240 11.090240 11.090240 90.000000 90.000000 90.000000
>>
>> ATOM -1: X=0.00000000 Y=0.00000000 Z=0.00000000
>> MULT= 1 ISPLIT=-2
>> In NPT= 781 R0=0.00001000 RMT= 2.0000 Z: 49.000
>>
>> LOCAL ROT MATRIX: 0.0000000 0.0000000 1.0000000
>> 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> ATOM -2: X=0.25000000 Y=0.25000000 Z=0.25000000
>> MULT= 1 ISPLIT=-2
>> P NPT= 781 R0=0.00010000 RMT= 2.0000 Z: 15.000
>>
>> LOCAL ROT MATRIX: 0.0000000 0.0000000 1.0000000
>> 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 8 NUMBER OF SYMMETRY OPERATIONS
>> 1 0 0 0.00000000
>> 0-1 0 0.00000000
>> 0 0-1 0.00000000
>> 1
>> 1 0 0 0.00000000
>> 0 0-1 0.00000000
>> 0-1 0 0.00000000
>> 2
>> -1 0 0 0.00000000
>> 0 1 0 0.00000000
>> 0 0-1 0.00000000
>> 3
>> -1 0 0 0.00000000
>> 0 0 1 0.00000000
>> 0-1 0 0.00000000
>> 4
>> -1 0 0 0.00000000
>> 0 0-1 0.00000000
>> 0 1 0 0.00000000
>> 5
>> -1 0 0 0.00000000
>> 0-1 0 0.00000000
>> 0 0 1 0.00000000
>> 6
>> 1 0 0 0.00000000
>> 0 0 1 0.00000000
>> 0 1 0 0.00000000
>> 7
>> 1 0 0 0.00000000
>> 0 1 0 0.00000000
>> 0 0 1 0.00000000
>> 8
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
>> <mailto:Wien at zeus.theochem.tuwien.ac.at>
>> https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=WpMS0L_jtI19kiPXo_QJrB9iBMQX1L9TeNePUM_x2Lw&s=4ayNKpiWdfxxYj0H3Q7Rpebbc7F13SXbRUZ8Zk5iaC8&e=
>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=WpMS0L_jtI19kiPXo_QJrB9iBMQX1L9TeNePUM_x2Lw&s=4ayNKpiWdfxxYj0H3Q7Rpebbc7F13SXbRUZ8Zk5iaC8&e=>
>> SEARCH the MAILING-LIST at:
>> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=WpMS0L_jtI19kiPXo_QJrB9iBMQX1L9TeNePUM_x2Lw&s=mVqpipfxiq1bmbMbUMXSnGFn2IQzz20XvEpWqcGva84&e=
>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=WpMS0L_jtI19kiPXo_QJrB9iBMQX1L9TeNePUM_x2Lw&s=mVqpipfxiq1bmbMbUMXSnGFn2IQzz20XvEpWqcGva84&e=>
>>
>>
>>
>>
>> --
>> 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 <http://www.numis.northwestern.edu> ;
>> Corrosion in 4D: MURI4D.numis.northwestern.edu
>> <http://MURI4D.numis.northwestern.edu>
>> Partner of the CFW 100% program for gender equity,
>> www.cfw.org/100-percent <http://www.cfw.org/100-percent>
>> Co-Editor, Acta Cryst A
>>
>>
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>> SEARCH the MAILING-LIST at:http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>
--
P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at/TC_Blaha
--------------------------------------------------------------------------
More information about the Wien
mailing list