After relaxation NEB images are same as initial or final image

[magnon963]

Dear VASP admin and users,

I have done many NEB calculations but first time facing this type of problem. I'm calculating Barrier for Stone-Wales defect (rotation of one C-C bond by 90 about bond's centre of mass) in graphene.
So I have 5 images in between initial and final image. Initial image is just perfect hexagonal graphene and final image has one rotated bond. 1-5 image has that C-C bond rotated by 15, 30, 45, 60 and 75 degree. These images I have generated using interpolate script.

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My INCAR file:

ISTART = 0 job : 0-new 1-cont 2-samecut
ICHARG = 2 charge : 1-file 2-atom 10-const
INIWAV = 1 electr : 0-lowe 1-rand

Electronic Relaxation 1
ENCUT = 550 eV
IALGO = 48
NELM = 220
NELMIN = 0
NELMDL = -8 # of ELM STEP m
EDIFF = 1E-04 stopping cretiria for ELM
GGA = PE
LDIAG = .T.
MAGMOM = 64*0.2

LMAXMIX = 4
INIMIX = 0
AMIX = 0.1
BMIX = 0.00001
AMIX_MAG= 0.4
BMIX_MAG= 0.000001
MAXMIX = -10

Ionic Relaxation
NSW = 150 number of steps for IOM #
EDIFFG = -0.01 stopping-criterion for IOM
ISIF = 2
ISYM = 2
ISPIN = 2
LCORR = .TRUE.
POTIM = 0.2
VOSKOWN = 1

NEB related tags
IMAGES = 5
ICHAIN = 0
SPRING = -5
IBRION = 1
LCLIMB = .TRUE.
LSCALAPACK = .FALSE.

SMASS = 2
NPAR = 25
NSIM = 1
LPLANE = .TRUE.

DOS related values:
SIGMA = 0.02
ISMEAR = 2 broad. in eV, -4-tet -1-fermi 0 gaus

NBAND = 150

LREAL = AUTO
=========================================================

KPOINTS:

Automatic mesh
0 ! number of k-points = 0 ->automatic generation scheme
Monkhorst Pack ! generate a Gamma centered grid
9 5 1 ! subdivisions N_1, N_2 and N_3 along recipr. l. vectors:q
0. 0. 0. ! optional shift of the mesh (s_1, s_2, s_3)

==============================================
After 60-70 ionic steps all the images are same as the initial geometry is.

It's very very surprising, because, it mean that all the images have dropped into initial minima, but how is it possible as we have projected out the parallel true force. Spring force is there just to keep images equidistant.

Is there any suggestion for this problem.

Thanking you for your help in this matter.

best regards,
PS

[admin]

for this case a set of fixed-geometry (for the rotation angles) calculations might be more appropriate I think