I am searching for Transition States through VASP. I have Optimized all my initial and final states, but now I have a problem for finding TS. Is there any way to change the distance between atoms?? Could I use Materials Studio,Vesta, Chem draw or other programs to solve this problem?? Or I should solve it in VASP environment??
And is there any way to solve this problem without changing the distances?? (For example changing some parameters in INCAR.)
You can use VTST to get TS befor CI-NEB, http://theory.cm.utexas.edu/vtsttools/
Qianchen Wang
Thank you.
I have visited there before, but I couldn't find any appropriate answer. I did many changes that they said but didn't work.
How are you computing the TS for the NEB ? Are you interpolating between the initial and final states with VTST ?
If so, you have to make sure that the atoms are arranged in the same order, that both states are oriented in the same way (could happen if both states come from different cif files for example) and that the atoms are all on the same side of the cell for both states (during relaxation, it is possible for atoms to exceed the boundaries of the cell. Since VASP is a periodic code, these atoms get refolded in the primary cell using the lattice vectors but as a result they get on a different side of the cell than the one they started at. A good way to check for this is to look at both states using p4vasp and check if some atoms are not traveling across the cell).
Dear Rémi Pasquier ,
Exactly I have this problem that you said. I have optimized the initial and final states, but the surface atoms are not in same positions.
How can I solve this problem ?? What should I do??
Regards
If I understood you well, some of your atoms are moving across the cell between the initial and final states, is that right ? If so, that means that the ionic relxation causes some of your atoms to exceed the boundaries of the cell for one of your states.
I sadly don't know about any fast way to solve this issue. You could try moving back the atoms to their correct position by hand before interpolating, using for example the p4vasp builder tool, but that might be time consuming. If you're using a supercell to simulate an isolated system, then you could try increasing slightly its size and reoptimizing the states to avoid any boundary crossing of the atoms.
Also, could you provide us with your initial and final states POSCAR/CONTCAR ?
Rémi Pasquier
Yes. Exactly, some of atoms have been moved.
I have changed the position of atoms to the same position with initial state then my job done successfully and converged, but the TS diagram was not correct.
So, I have attached my initial and final files here, I hope that a solution can be find.
Thank you.
Sorry for the late answer, I had quite a bit of work to do.
I had a look at your POSCARs, some atoms do indeed move but you did say that you changed their positions to the correct ones so that should not be the issue.
Also, you're telling me that the TS diagram is not correct : what do you mean (wrong barrier value ?)
Besides, can I have a look at your INCAR ?
Dear Rémi Pasquier ,
Thank you.
I decide to do this in other way.
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