[Wien] Structural relaxation in hybrid calculations

[Dr. K. C. Bhamu]

Dear Dr. Tran,

I see a workaround for structural relaxation for YS-PBE0.

PBE optimization with "min_lapw ...." or "run_lapw ..... -min' will give
relaxed structure at different volumes.

Make another dir and initialize the case and copy all relaxed structure to
pwd and do optimization with YS-PBE0 without relaxation and run optimize.job

Could you please verify this workaround?

Regards
Bhamu




On Sat, Aug 4, 2018 at 8:30 PM, <tran at theochem.tuwien.ac.at> wrote:

> No
>
> On Saturday 2018-08-04 16:22, Dr. K. C. Bhamu wrote:
>
> Date: Sat, 4 Aug 2018 16:22:20
>> From: Dr. K. C. Bhamu <kcbhamu85 at gmail.com>
>> Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.
>> at>
>> To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
>> Subject: Re: [Wien] regarding mixing parameter in hybrid calculations
>>
>> Thanks Dr. Tran,
>>
>>
>>
>> My mistake, the standard value is 0.25!!
>>
>> Yes, I saw the link you provided (response was on my own queries).
>>
>>
>> What is advised there is:
>>
>>
>> "What you get from the optic calculation (the case.epsilon) file is only
>> the electronic part  (and not even the whole electronic part) of the
>> dielectric
>> constant."
>>
>> To get the ionic part of the static dielectric  constant you would need
>> to do the BERRYPI calculations to get Born effective charges tensors."
>>
>>
>>
>> Do you have any previous experience on how much the properties may vary
>> if we avoid the "ionic part of the dielectric constant'?
>>
>>
>>
>> Thanks and regards
>>
>>
>>
>>
>>
>>
>>
>>
>> On Sat, Aug 4, 2018 at 7:13 PM, <tran at theochem.tuwien.ac.at> wrote:
>>      Hi,
>>
>>      First, the standard value is 0.25 and not 0.025.
>>
>>      For the dielectric constant, there was alreday some explanations
>> here:
>>      https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.a
>> t/msg14936.html
>>      https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.a
>> t/msg14875.html
>>
>>      alpha_opt at V=V_exp means that the dielectric function (and
>> alpha_opt)
>>      is calculated only at V_exp and then used for all other volumes.
>>      See also this:
>>      https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.a
>> t/msg15531.html
>>
>>      No, it is not mandatory to do PBE calculation before YS-PBE0.
>> Starting
>>      YS-PBE0 from PBE electron density (case.clmsum) may just help to
>> reduce
>>      the number of SCF iterations with YS-PBE0.
>>
>>      Of course it is possible to optimize lattice parameters with YS-PBE0.
>>      You just need to add the "-hf" option in the optimize.job file.
>>      What is not possible with YS-PBE0 is to optimize the position of
>>      atoms in the unit cell (because the forces are not implemented for
>>      YS-PBE0).
>>
>>      FT
>>
>>
>>      On Saturday 2018-08-04 14:46, Dr. K. C. Bhamu wrote:
>>
>>            Date: Sat, 4 Aug 2018 14:46:02
>>            From: Dr. K. C. Bhamu <kcbhamu85 at gmail.com>
>>            Reply-To: A Mailing list for WIEN2k users <
>> wien at zeus.theochem.tuwien.ac.at>
>>            To: A Mailing list for WIEN2k users <
>> Wien at zeus.theochem.tuwien.ac.at>
>>            Subject: [Wien] regarding mixing parameter in hybrid
>> calculations
>>
>>            Dear Dr. Tran,
>>
>>            In the recent past, I did some calculations using YS-PBE0 for
>> MgO and results were well reproduced (wien2k Exercise).
>>
>>            I just read your paper (J. Phys.: Condens. Matter 25 (2013))
>> and get to know that we can control the mixing parameter using various
>>            ways.
>>
>>            1) Standard value (0.025)
>>            2) By fitting  (alpa_opt)
>>            3) alpa_opt (V=V_exp)
>>
>>            I have queries for option 2 and 3 alpa:
>>
>>            2) If I am not wrong (after having a detailed search), the
>> value of dielectric constant used to get alpa_opt is the value of dielectric
>>            constant from
>>            Rel(epsilon) at energy 0.013610 eV, right?
>>
>>            3) How to get alpa_opt at V-V_exp?
>>
>>
>>
>>
>>
>>            My next query is:
>>
>>            It is reported in the Wien2k exercise that to do YS-PBE0
>> calculations we need to do a simple PBE scf.  So if we really need to
>> perform
>>            PBE calculations before
>>            going to YS-PBE0, I am wondering how to use YS-PBE0 to
>> optimize the lattice parameters and to get structural properties?
>>
>>
>>            Could you please advice me on my concerns?
>>
>>            * in above text "_" means an underscore.
>>
>>
>>            regards
>>
>>
>>
>>
>>      _______________________________________________
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>> en at zeus.theochem.tuwien.ac.at/index.html
>>
>>
>>
>>
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