UT theoretical chemistry code forum

I have an issue with SSNB to study a martensitic phase transition in a metal oxide and any tips would be very appreciated.
In all cases I did linear interpolation between the first and final states. First I tried to do energy cutoff convergence on 5 intermediate images. The lower energy cuttoffs (<450eV) converge to a saddle point, while the higher ones keep oscillating (every now and then the max force on an atom in an intermediate image shoots up to 50+ ev/A and then go down after few ionic steps).
So I tried these high energy cuttoff on larger number of images (11), and again I observe these oscillations in the forces.
Any suggestions?

The VTST version I use is VTST: version 3.0b, (11/11/12), and here is a typical INCAR:

SSNEB Metal Oxide
ISTART=0 ; ICHARG = 2
ISMEAR = 0 ; SIGMA =0.05
ENCUT= 600
IBRION=3
POTIM=0
IOPT=3 ; ISIF=3; NSW=5000
EDIFF = 1E-06
EDIFFG = -0.01
LWAVE = .FALSE.
LCHARG= .FALSE.
PREC=Accurate
IMAGES=5
SPRING=-5
LCLIMB=.TRUE.
NPAR=1
LNEBCELL=.TRUE.
TIMESTEP=0.04

A related question, is ISYM=0 recommended for this type of calculations?

Thank you!

First, yes, I suggest always using ISYM=0 for NEB calculations unless you really know what you are doing.

Poor convergence with a high energy cutoff sounds strange. Check to make sure that the electronic iterations are converging. Then, I would try reducing the TIMESTEP variable to see if you can converge (even slowly) with the high cutoff.

That's all I can think of; we would have to look at the output for other suggestions.

Thank you for your help! It was indeed the electronic convergence that lead the high energy cutoff calculations to show this wild behavior. I started from scratch using cutoff 600 eV , EDIFF = 1E-08, and TIMESTEP=0.03. This calculation while is still running, seems to be ok.