[Wien] Volume optimization of Sulphur

[shamik chakrabarti]

I think we should multiply the printed volume by 3 to get the actual volume
as the cell described in rhombohedral lattice is 3 times larger than the
hexagonal unit cell...I am sending a link which gives this clue

            http://www.globalsino.com/EM/page3546.html

Please correct me if I am wrong!

with regards,

On Tue, 10 Mar 2020 at 15:22, Tran, Fabien <fabien.tran at tuwien.ac.at> wrote:

> Probably. In case.struct, the lattice constants and angles are for the
> hexagonal cell, while atoms positions are with respect to rhombohedral.
>
>
> ------------------------------
> *From:* Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of
> shamik chakrabarti <shamik15041981 at gmail.com>
> *Sent:* Tuesday, March 10, 2020 10:46 AM
> *To:* A Mailing list for WIEN2k users
> *Subject:* Re: [Wien] Volume optimization of Sulphur
>
> It may be a clue for solving the above problem;
>
>               In the struct file (as seen in the GUI) a line remains added
> :   "positions must be specified in rhombohedral coordinates!"
>
> Looking forward to your response eagerly.
>
> with regards,
>
> On Tue, 10 Mar 2020 at 14:51, shamik chakrabarti <shamik15041981 at gmail.com>
> wrote:
>
>> 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
>>> _______________________________________________
>>> 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
>>>
>>
>>
>> --
>> 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
> _______________________________________________
> 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
>


-- 
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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