[Wien] Rhombhohedral coordinates needed in simulation of LiNiO2

[shamik chakrabarti]

Dear Prof. Gavin,

     Apart from that warning, rests are progressing well. Also, the
structure looks similar to earlier DFT calculation. I will go with this.

with regards,

On Sun, 28 Apr 2024 at 21:26, Gavin Abo <gabo13279 at gmail.com> wrote:

> Sorry, missed a word, that should read "not an error message"
> On 4/28/2024 9:47 AM, Gavin Abo wrote:
>
> 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 NOT 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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-- 
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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