UT theoretical chemistry code forum

Dear all, I have a question about how to obtain the intermediate states

after finding the saddle point with DIMER method. If the NEB method is

used, it is easy to get the intermediate states, because before starting a

neb calculation a chain of states linking the initial and finals states should

be given. However, for the dimer calculation, only two initial states are

need and two images near the saddle point are obtained. So if I want to

know the intermediate states between the initial state and saddle point,

what should I do?

Whether I still need to use the initial state and the saddle point as the

starting images to perform a neb calculation?

On the other hand, I check the energy of each image printed in OUTCAR,

and find the energy first goes up and then down to the saddle point. So I

think none of the structures generated in the process of searching the

saddle point recorded in OUTCAR is the intermediate state between the

initial state and the saddle point, right?

Thanks a lot!

Once you have a saddle use a dimer calculation, you can find the associated minima by doing a conservative minimization on either side of the saddle. You can generate initial configurations for these two minimization runs using our interpolate.pl script, for example:

interpolate.pl 01/POSCAR 02/POSCAR -100.0
interpolate.pl 01/POSCAR 02/POSCAR 100.0

This minima could be your initial and final states, or some intermediate(s) along the way.

that is great!

If I want to know the energy of intermediate state, I only need to perform

a common VASP static calculations, right?

No, you need to do a minimization from each side of the saddle point to the connecting minima on either side of it.

Thanks a lot for your reply so soon!

Now I know how to do it!

Thank you very much again!