Re: About MD.Fixed.XYZ ( No.1 ) |
- Date: 2016/06/23 13:50
- Name: T. Ozaki
- Hi,
Please provide more information. Otherwise, it is difficult to figure out what happened in your calculation.
Regards,
TO
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Re: About MD.Fixed.XYZ ( No.2 ) |
- Date: 2016/06/26 05:35
- Name: Guilherme Maia <guisawyer@yahoo.com.br>
- Hi T. Ozaki,
Ok, I'll try explain what is happening...
I started to do the study of the PTO (PbTiO3)
Space group name P 4 m m Space group number 99
and the Wyckoff Positions only allowed me to relax in the z-coordinate! To keep the symmetry!! (Ref http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-wp-list )
The unit cell of the PTO are:
1 Pb Pb1 0.00000 0.00000 0.00000 2 Ti Ti1 0.50000 0.50000 0.52810 3 O O1 0.50000 0.00000 0.61300 4 O O2 0.50000 0.50000 0.13390
But to do the Simulation I can't use only the unit cell... I have to specify more atoms, in this case:
1 Pb Pb1 0.000000000 0.000000000 0.000000 2 Ti Ti1 0.500000000 0.500000000 0.528100 3 O O1 0.500000000 0.000000000 0.613900 4 O O1 0.000000000 0.500000000 0.613900 5 O O2 0.500000000 0.500000000 0.133900
So the Atom 3 and 4 have to move the same distance to keep the symmetry...
I had check the out of the file.dat# and the Atom 3 and 4 don't appear with the same.. but was almost the same.. I think I'm being too hard on it. the difference its very small...
The position after :
1 Pb 0.00000000000000 0.00000000000000 0.03315150938798 7.0 7.0 2 Ti 0.50000000000000 0.50000000000000 0.54504033072155 6.0 6.0 3 O 0.50000000000000 0.00000000000000 0.60553117155627 3.0 3.0 4 O 0.00000000000000 0.50000000000000 0.60553199091178 3.0 3.0 5 O 0.50000000000000 0.50000000000000 0.09935469249243 3.0 3.0
the z-coordinate of the atoms 3 e 4 I can say are the same!!! So, its OK!!
But, have some kind of option that make in this case, the atoms 3 and 4 move exactly the same?!
I hope its clear now!! Best Regards!
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