UT theoretical chemistry code forum

Sorry, I thought what you posted were neb.dat from nebbarrier.pl

I think "FMAGFLAG=T" just means converging based on magnitude of the total force rather than converging based on the max atom force. IALGO sets the algorithm used for electronic step. As long as the electronic step converges within NELM, IALGO will not affect the ionic steps. But if someth...

Maybe try to add ICHAIN=0

Has the VTSTCODE been updated and complied in the last one month?

Is the OUTCAR in each image folder finished?

Those should be the velocities of the atoms. It doesn't matter in SSNEB calculation. There is no surprise that the converged structures are similar to the linear interpolated ones, since only two atoms are included in the supercell. I think the barrier should be lower than the initial guess. You can...

Seems like that you missed POTIM = 0.0
But I am not sure whether the error come from this. Also try to set a larger ENCUT (1.3*ENMAX).

Can you post your INCAR so that we can look into it ?

Yes, the default is PSTRESS = 0, in the unit of 0.1GPa (kB) . It is not necessary to set PSTRESS.

You may need to update to the latest version of VTSTCODE.

LNEBCELL is the flag to turn on solid state NEB, which includes the cell variables in the reaction coordinates.
The paper on the SSNEB method can be found here:
http://theory.cm.utexas.edu/henkelman/p ... 074103.pdf

Yes, you can use the solid state NEB by setting LNEBCELL = True, ISIF=3, and IOPT =3
There are details discussed here:
viewtopic.php?f=2&t=1136

The spline mep curve can be misleading sometimes. As long as the forces converged (usually 0.01 is enough), the climbing image is at the saddle point. The higher energy section on mep.eps is just the fault of spline.

This lecture note is good:
http://makarov.cm.utexas.edu/resources/ ... theory.pdf

You can get the climbing image number from neb.dat. The CONTCAR file in the folder with the name of that number is what you want.
As along as the EDIFFG is small enough, this saddle point structure is accurate. Do not optimize when you calculate the frequency.

Yes, it is enthalpy in TSASE. I just compared the results between TSASE and VTST. Replacing the energies in nebss.dat with enthalpies from TSASE smoothes the path. I think this will solve your problem. You can do it by hand if your are in hurry. Just read enthalpy of each image from OSZICAR and divi...