UT theoretical chemistry code forum

Hi,

I am running a NEB run about O dimer disassociate on Pt(111) surface. the end points are well converged.
I use QM (MAXMOVE=0.2, TIMESTEP=0.1) for the first several tens of steps, the force dropped. Then I continued
also using QM with the same parameters, but this time the force gradually get higher and higher. I post force of the middle image
below (total 3 images):
NEB: projections on to tangent (spring, REAL) 2.040819 0.195098
NEB: projections on to tangent (spring, REAL) 2.049163 0.211668
NEB: projections on to tangent (spring, REAL) 2.069592 0.233924
NEB: projections on to tangent (spring, REAL) 2.104807 0.234295
NEB: projections on to tangent (spring, REAL) 2.149536 0.241508
NEB: projections on to tangent (spring, REAL) 2.207955 0.242442
NEB: projections on to tangent (spring, REAL) 2.281905 0.253892
NEB: projections on to tangent (spring, REAL) 2.362500 0.234770
NEB: projections on to tangent (spring, REAL) 2.423143 0.311858
NEB: projections on to tangent (spring, REAL) 2.438558 0.268266
NEB: projections on to tangent (spring, REAL) 2.490136 0.287904
NEB: projections on to tangent (spring, REAL) 2.565051 0.288561
NEB: projections on to tangent (spring, REAL) 2.650972 0.323155
NEB: projections on to tangent (spring, REAL) 2.736606 0.309052
NEB: projections on to tangent (spring, REAL) 2.803518 0.364417
NEB: projections on to tangent (spring, REAL) 2.843273 0.337603
NEB: projections on to tangent (spring, REAL) 2.886076 0.384782
NEB: projections on to tangent (spring, REAL) 2.934717 0.380262
NEB: projections on to tangent (spring, REAL) 2.998825 0.430638
NEB: projections on to tangent (spring, REAL) 3.075387 0.429859
NEB: projections on to tangent (spring, REAL) 3.161653 0.502243
NEB: projections on to tangent (spring, REAL) 3.242262 0.501781
NEB: projections on to tangent (spring, REAL) 3.335677 0.588406
NEB: projections on to tangent (spring, REAL) 3.437467 0.604625
NEB: projections on to tangent (spring, REAL) 3.557486 0.704536
NEB: projections on to tangent (spring, REAL) 3.692415 0.756878
NEB: projections on to tangent (spring, REAL) 3.852527 0.900182
NEB: projections on to tangent (spring, REAL) 4.020130 0.980385
NEB: projections on to tangent (spring, REAL) 4.224614 1.184891
NEB: projections on to tangent (spring, REAL) 4.443224 1.333503
NEB: projections on to tangent (spring, REAL) 4.709432 1.589459
NEB: projections on to tangent (spring, REAL) 4.995635 1.798413
NEB: projections on to tangent (spring, REAL) 5.320550 2.074046
NEB: projections on to tangent (spring, REAL) 5.635408 2.249360
NEB: projections on to tangent (spring, REAL) 5.888888 2.285011
NEB: projections on to tangent (spring, REAL) 6.032586 1.840624
NEB: projections on to tangent (spring, REAL) 5.965715 1.408348

all three images have the same trends. Can anyone tell me what's going on? and Should I decrease the TIMESTEP and continue the run or some other problem happens?

INCAR file:
SYSTEM = PtO2TS
ISTART = 0
ICHARG = 2
LREAL = AUTO
ISIF = 2
ISPIN = 2
ENCUT = 400
ALGO=FAST
NSIM=4
EDIFFG = -0.01
NSW = 50
IBRION = 3
POTIM = 0
ICHAIN = 0
IMAGES = 3
SPRING = -5
LCLIMB = .TRUE.
IOPT =3
MAXMOVE=0.2
TIMESTEP=0.1
ISMEAR = 1; SIGMA = 0.1
LPLANE = .TRUE.
NPAR = 8
LCHARG=.FALSE.
MAXMIX=40;