NEB calculation

[akundu]

Hi,

I am trying to calculate the transition path between the structure of A, B and C. Among three structure, C is the ground state structure, and A and B is the metastable structure. When I am trying to calculate the transition path between A and B, there are few images whose energy is close to C. I think, it indicates that the transition is happening through the ground state C. But I want to look at the direct transition path between A and B. How can I get the direct transition path? Also, please let me know if I am doing anything wrong. The INCAR is given below

ISTART = 0
ICHARG = 2
PREC = Accurate
ISMEAR = 0
SIGMA = 0.01
EDIFF = 1.0E-4
EDIFFG = -0.01
POTIM = 0.05
ENCUT = 500
IALGO = 38
ISYM = -1
IBRION = 1
NSW = 200
NELM = 200
NELMIN = 6
ISIF = 2

LWAVE = .FALSE.
LCHARG = .FALSE.


ICHAIN = 0
IMAGES = 7
SPRING = -5
LCLIMB = .TRUE.
LTANGENTOLD = .FALSE.
LDNEB = .FALSE.
LNEBCELL = .FALSE.
LSCALAPACK = .FALSE.

[graeme]

The NEB will converge to the what is, in some sense, the closest minimum energy path to your initial path. It is certainly possible that two states (e.g. A and B) are not directly connected by a single saddle point and that the minimum energy path connecting them goes through a intermediate state C. If that happens, you can try different initial paths which follows another reaction mechanism, but you can not demand that two states be directly connected.

Another approach is to use single-ended searches, such as the dimer method, to find saddles that correspond to escape paths from A and/or B. With this technique you can discover reaction mechanisms and product states that may be unanticipated.