As far as I know, w2web is not able to automatically detect yet if you
have entered the atomic positions correctly for space group 166. So,
the "positions must be specified in rhombohedral coordinates!" is an
error message but a reminder text that will always be there whether you
enter position correctly or incorrectly. Thus, you have to carefully
check for yourself that you have entered the position correctly.
As you might recall from the post at [1], WIEN2k is a bit unusual in
that for the struct file it needs hexagonal lattice constants but
rhombohedral for the atomic positions for an R lattice space group such
as 166 R-3m.
For LiNIO2, you should double check, but I believe the both lattice
constants and atomic positions in the hexagonal setting are:
Initial Setting: R-3m:h (No. 166)
166
5.404616 5.404616 26.569550 90 90 120 <= This is the hexagonal lattice
parameters needed for the struct file of WIEN2k
3
Li 1 3a 0.000000 0.000000 0.000000 <= These are the
hexagonal atomic positions, which would be incorrect to use for WIEN2k
Ni 1 3b 0.000000 0.000000 0.500000
O 1 6c 0.000000 0.000000 0.240984
Using SETSTRU [2], its equivalent in the rhombohedral setting should be:
Final Setting: R-3m:r (No. 166)
166 #R-3m:r
9.3901 9.3901 9.3901 33.45 33.45 33.45 <= These are the rhombohedral
lattice parameters, which would be incorrect to use for WIEN2k
3
Li 1 - 0.000000 0.000000 0.000000 <= These are the
rhomboderal atomic positions needed for the struct file of WIEN2k
Ni 1 - 0.500000 0.500000 0.500000
O 1 - 0.240984 0.240984 0.240984
In your LiNiO2_opt.struct, I see:
a = 5.404616 bohr in hexagonal setting
b = 5.404616 bohr in hexagonal setting
c = 26.569550 bohr in hexagonal setting
alpha = 90.000000 deg in hexagonal setting
beta = 90.000000 deg in hexagonal setting
beta = 120.000000 deg in hexagonal setting
Li x=0.00000000 y=0.00000000 z=0.00000000 in rhombohedral setting
Ni z=0.50000000 y=0.50000000 z=0.50000000 in rhombohedral setting
O x=0.24098400 y=0.24098400 z=0.24098400 in rhombohedral setting
[1]
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05554.html
[2] https://www.cryst.ehu.es/cryst/setstru.html
On 4/28/2024 8:00 AM, shamik chakrabarti wrote:
Dear Wien2k users,
I want to simulate properties of LiNiO2. However, adopting
the structure (file attached) by bringing it into rhombohedral axis in
Vesta, when I copy the cif file into the working directory &
converting it into a struct file, after save structure, it complains
about
" positions must be specified in rhombohedral coordinates!"
Please guide.
with regards,
--
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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