check NEB in VASP

Vasp transition state theory tools

Moderator: moderators

Post Reply
boy7478
Posts: 6
Joined: Mon Mar 26, 2007 2:52 pm

check NEB in VASP

Post by boy7478 »

hi everyone,
i would like to know how to check if my version of VASP has included the code from Henkelman group, and from which directory i can check it.

thanks,
Boy
graeme
Site Admin
Posts: 2291
Joined: Tue Apr 26, 2005 4:25 am
Contact:

Post by graeme »

In the latest versions of our code, there will be a print statement in the OUTCAR that looks like

VTST: version x.xx

In the current and earlier versions, you can tell if the magnitude of the forces are printed in the OUTCAR

FORCES: max atom, RMS

Also, if you have access to the code directory, you can see if any of the additional modules are present, including, neb.F, dimer.F, dynmat.F, and in the most recent code, opt.F, cg.F, and lbfgs.F
boy7478
Posts: 6
Joined: Mon Mar 26, 2007 2:52 pm

Post by boy7478 »

Hmm..
Well..then my version has not modified yet..
Yes I can access the code directory..shall i just download from the web and copy them to the code directory?

An additional question :
What value would you suggest for ionic step (NSW) for NEB calculation?

Thanks,
Boy
graeme
Site Admin
Posts: 2291
Joined: Tue Apr 26, 2005 4:25 am
Contact:

Post by graeme »

Instructions for downloading and building the code within vasp is at
http://theory.cm.utexas.edu/vtsttools/downloads/

The number of ionic steps (NSW) is a good way to limit the length that a job can run, but the value is not particularly important if you keep an eye on your job. If it's set too small, the job will stop before convergence and it will have to be restarted. If set too large, it can run too long before a problem is caught. Either way, it's not a big problem.

It can be useful to set a small NSW (10-20) at the start of an NEB calculation, if the initial forces are very high. You can use a conservative optimizer (e.g. potim=0.01 and ibrion=3) for this stage. Then do a normal run with NSW around 500 using an aggressive optimizer to converge the NEB.
Post Reply