I think F. Tran already gave you the hint about "primitive R cell" and
"conventional H cell".
The volume of the R cell is 3 times smaller than that of the H cell.
Wien2k gives H lattice parameters, but makes the calculation internally
in R cell.
So yes, if you get an equilibrium volume which does not fit your
expectations, it is because of your wrong assumptions aber the actual
lattice.
It is the same as for a FCC cubic cell: What is the volume of the
primitive (R) cell of an FCC lattice: it is NOT a**3, but a**3 / 4.
--------------------
Besides this: the optimize scribt gives you a volume, but of course also
total energies and you can easily see, which of your struct files
corresponds (nearly) to the optimized volume (the one with the lowest
energy). And you find the corresponding a,c values directly in this
struct file.....
It can't be that difficult to get the optimized lattice parameters.
PS: Please read the UG (struct file) about R-lattices
On 3/10/20 11:03 AM, shamik chakrabarti wrote:
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.t...@tuwien.ac.at
<mailto:fabien.t...@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-boun...@zeus.theochem.tuwien.ac.at
<mailto:wien-boun...@zeus.theochem.tuwien.ac.at>> on behalf of
shamik chakrabarti <shamik15041...@gmail.com
<mailto:shamik15041...@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
<shamik15041...@gmail.com <mailto:shamik15041...@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.t...@tuwien.ac.at <mailto:fabien.t...@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-boun...@zeus.theochem.tuwien.ac.at
<mailto:wien-boun...@zeus.theochem.tuwien.ac.at>> on behalf
of shamik chakrabarti <shamik15041...@gmail.com
<mailto:shamik15041...@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
<shamik15041...@gmail.com <mailto:shamik15041...@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@zeus.theochem.tuwien.ac.at
<mailto:Wien@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@zeus.theochem.tuwien.ac.at <mailto:Wien@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
_______________________________________________
Wien mailing list
Wien@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: bl...@theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at/TC_Blaha
--------------------------------------------------------------------------
_______________________________________________
Wien mailing list
Wien@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
