Fixed atoms move
Moderators: Global Moderator, Moderator
Fixed atoms move
I have a system composed of 20 Fe atoms in a 5-layer 2x2 stack (bcc) with the bottom three layers frozen using "F F F" after the atom's coordinate listing in the POSCAR file. However, when I look at the result, the "fixed" atoms have moved by almost 0.1 Angstrom! Further, it is not a constant translation of all atoms. Am I missing something or is there a bug in VASP that moves these atoms? I am very concerned because the system is tangibly changed by such movement.
Last edited by hortophilus on Tue Sep 30, 2008 4:48 am, edited 1 time in total.
-
- Sr. Member
- Posts: 339
- Joined: Mon Apr 24, 2006 9:07 am
- License Nr.: 173
- Location: Gothenburg, Sweden
Fixed atoms move
1. Have you checked if you have added the Selective dynamics tag correctly to the POSCAR-file?
2. Check if you do relax the volume/shape of the unit cell. Since the "F F F" locks the direct coordinates the positions might change if the basis vectors change during the run.
If none of the above helps, please provide your INCAR+POSCAR files so that we can give you a more detailed response.
Cheers
/Dan
<span class='smallblacktext'>[ Edited Tue Sep 30 2008, 07:28AM ]</span>
2. Check if you do relax the volume/shape of the unit cell. Since the "F F F" locks the direct coordinates the positions might change if the basis vectors change during the run.
If none of the above helps, please provide your INCAR+POSCAR files so that we can give you a more detailed response.
Cheers
/Dan
<span class='smallblacktext'>[ Edited Tue Sep 30 2008, 07:28AM ]</span>
Last edited by forsdan on Tue Sep 30, 2008 5:25 am, edited 1 time in total.
Fixed atoms move
I did not have the selective dynamics tag, so I will try it with the tag.
Last edited by hortophilus on Wed Oct 01, 2008 12:45 am, edited 1 time in total.
-
- Administrator
- Posts: 2921
- Joined: Tue Aug 03, 2004 8:18 am
- License Nr.: 458
Fixed atoms move
this explains the behaviour. If Selective dynamics is not set, the Ts and Fs are ignored.
Last edited by admin on Wed Oct 01, 2008 9:25 am, edited 1 time in total.