[Wien] Force Convergence criterion during SCF

[Ghosh SUDDHASATTWA]

Hi Xavier, 

Thanks for your detailed response on the space group. 

Thanks as well for the recommendations 

Suddhasattwa

 

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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 12:31 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Force Convergence criterion during SCF

 

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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