Hi, I am trying to run a NVE simulation of an atom impinging on a cluster. I find that even within 1 time step, the kinetic energies of the atom is changing quite a bit. So, I simply tried to put one atom in a box (with a certain velocity) and run the same NVE simulation. Even then I find the kinetic energy changing in just 1 time step. Is there some problem with my input file? Any help is appreciated. &GLOBAL PROJECT Na-md RUN_TYPE MD PRINT_LEVEL MEDIUM WALLTIME 1.40000000E+04 &END GLOBAL &MOTION &MD ENSEMBLE NVE STEPS 100000 TIMESTEP 0.5 &PRINT FORCE_LAST .TRUE. &END PRINT &END MD &PRINT &RESTART ADD_LAST NUMERIC &END RESTART &VELOCITIES ADD_LAST NUMERIC &END VELOCITIES &END PRINT &END MOTION &FORCE_EVAL METHOD Quickstep &DFT BASIS_SET_FILE_NAME ~/cp2k/tests/QS/GTH_BASIS_SETS POTENTIAL_FILE_NAME ~/cp2k/tests/QS/POTENTIAL UKS &MGRID CUTOFF 400 NGRIDS 4 REL_CUTOFF 25 &END MGRID &QS EPS_DEFAULT 1.0E-12 EPS_GVG 1.0E-6 EPS_PGF_ORB 1.0E-6 &END QS &SCF EPS_SCF 1.0E-6 MAX_SCF 500 SCF_GUESS atomic &OT ON MINIMIZER DIIS PRECONDITIONER FULL_ALL &END OT &END SCF &XC &XC_FUNCTIONAL BLYP &END XC_FUNCTIONAL &END XC &POISSON POISSON WAVELET PERIODIC NONE &END POISSON &END DFT &SUBSYS &TOPOLOGY &CENTER_COORDINATES T &END CENTER_COORDINATES &END TOPOLOGY &CELL PERIODIC NONE ABC 30.000 30.000 30.000 &END CELL &COORD Na -22.000000000000000 0.0000000000000000 0.0000000000000000 &END COORD &VELOCITY 0.0020569591937 0.0000000000000 0.0000000000000 &END VELOCITY &KIND Na BASIS_SET DZVP-GTH POTENTIAL GTH-BLYP-q9 &END KIND &END SUBSYS &END FORCE_EVAL Thanks a lot in advance. LS