[Wien] Force Convergence criterion during SCF

[Rocquefelte]

Dear Suddhasattwa,

Here I copy the general position and the special positions corresponding 
to this space group.

Positions:
24r    1    x, y, z
12q    m..    x, y, 0.5
12p    m..    x, y, 0
12o    .m.    x, 2x, z
12n    ..m    x, 0, z
6m    mm2    x, 2x, 0.5
6l    mm2    x, 2x, 0
6k    m2m    x, 0, 0.5
6j    m2m    x, 0, 0
6i    2mm    0.5, 0, z
4h    3m.    0.33333, 0.66667, z
3g    mmm    0.5, 0, 0.5
3f    mmm    0.5, 0, 0
2e    6mm    0, 0, z
2d    -6m2    0.33333, 0.66667, 0.5
2c    -6m2    0.33333, 0.66667, 0
1b    6/mmm    0, 0, 0.5
1a    6/mmm    0, 0, 0

If an atom is on 1a or 1b or 2c or 2d or 2e or 3f or 3g position, then 
the forces along x, y and z are imposed to be zero for symetry reasons 
(no degree of freedom).
In the case of 4h position, you will have forces only along z.

I would like to draw your attention about the fact that your question is 
not related to wien2k but to the way you understand and use space group 
and symetry in solid.
I would strongly recommend you to learn more about geometrical 
crystallography before looking at complex systems.

Regards

Xavier

Ghosh SUDDHASATTWA a écrit :
>
> Hi Xavier,
>
> The Pearson symbol is hP3 and the space grup is P6/mmm, No. 191
>
>  
>
> Suddhasattwa Ghosh
>
>  
>
>  
>
>  
>
> ------------------------------------------------------------------------
>
> *From:* wien-bounces at zeus.theochem.tuwien.ac.at 
> [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] *On Behalf Of 
> *Rocquefelte
> *Sent:* Wednesday, January 13, 2010 11:38 AM
> *To:* A Mailing list for WIEN2k users
> *Subject:* Re: [Wien] Force Convergence criterion during SCF
>
>  
>
> Dear Suddhasattwa,
>
> It seems (but again we have very few information in your email) that 
> you only have special positions, for which all the coordinates are 
> constrained (not allowed to change).
> In such situation there are, of course, no forces to calculate because 
> of symetry reasons.
>
> Regards
>
> Xavier
>
>
> Ghosh SUDDHASATTWA a écrit :
>
> Dear Wien2k users,
>
> I did SCF using both charge and energy convergence criterion and SCF 
> converged successfully.
>
> I again applied force convergence criterion of 1mRy/atom and it still 
> converged but with a comment in the beginning
>
> "Force convergence not possible, Forces not present.
>
> When I tried to analyse the SCF file, it did not give any value of FOR
>
>  
>
> Suddhasattwa
>
>  
>
>  
>
>
> ------------------------------------------------------------------------
>
>
>  
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