[Wien] Volume optimization of Sulphur

[shamik chakrabarti]

Dear Prof. Tran,

                  a^2 c Sin 60 is the volume of the rhombohedral cell
having lattice parameter a=b & c. I have used the same formula for
hexagonal SnS2 and got very good results. I think somehow the printed
volume  is almost 1/2.8 th of the actual value needed. I guess it is
something related to R_3 crystal system...........

with regards,

On Tue, 10 Mar 2020 at 14:36, Tran, Fabien <fabien.tran at tuwien.ac.at> wrote:

> WIEN2k does the calculations in the primitive unit cell, whose volume is
> given by :VOL in case.scf
>
> Is a^2 c Sin 60 not the volume of the conventional cell?
>
> You can visualize the primitive and conventional cells of case.struct with
> xcrysden (press F3 or F4).
>
>
> ------------------------------
> *From:* Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of
> shamik chakrabarti <shamik15041981 at gmail.com>
> *Sent:* Tuesday, March 10, 2020 9:58 AM
> *To:* A Mailing list for WIEN2k users
> *Subject:* Re: [Wien] Volume optimization of Sulphur
>
> Dear Wien2k users,
>
>                               I am also certain that I am not doing any
> mistake in the formula  of Volume=a^2 c Sin 60. However, the V0 printed in
> the window showing the fitted BM curve is coming much less than that
> expected from  a^2 c Sin 60 . What could be the cause? Is it related to the
> space group R_3 (space group no. 148)?
>
> Looking forward to your reply eagerly.
>
> with regards,
>
>
> On Tue, 10 Mar 2020 at 13:11, shamik chakrabarti <shamik15041981 at gmail.com>
> wrote:
>
>> Dear Lyudmila Sir,
>>
>>                          To remove the confusion I am sending the struct
>> file which have been used in our simulation. I have good results as far as
>> the volume optimization curve is concerned. However, while calculating the
>> lattice parameters using the formula V = a^2 c sin60 I got the low value of
>> lattice parameters. My query is
>> (1) Whether I have done something wrong in the formula itself?
>> (2) While GGA is better than nlvdw in this case?
>>
>> with regards,
>>
>> --
>> Dr. Shamik Chakrabarti
>> Research Fellow
>> Department of Physics
>> Indian Institute of Technology Patna
>> Bihta-801103
>> Patna
>> Bihar, India
>>
>
>
> --
> Dr. Shamik Chakrabarti
> Research Fellow
> Department of Physics
> Indian Institute of Technology Patna
> Bihta-801103
> Patna
> Bihar, India
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-- 
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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