Dear all, I am trying to calculate free energy using umbrella sampling. When i am using restraint option, after wave function optimazation, it is terminating with following error. *** SCF run converged in 45 steps *** Electronic density on regular grids: -24.0000073560 -0.0000073560 Core density on regular grids: 24.0000000488 0.0000000488 Total charge density on r-space grids: -0.0000073072 Total charge density g-space grids: -0.0000073072 Overlap energy of the core charge distribution: 0.00000019007040 Self energy of the core charge distribution: -141.33094186512190 Core Hamiltonian energy: 40.50915002552838 Hartree energy: 58.68463253766369 Exchange-correlation energy: -12.74086812588142 Dispersion energy: -0.00168560914124 Total energy: -54.87971284688209 outer SCF iter = 1 RMS gradient = 0.35E-05 energy = -54.8797128469 outer SCF loop converged in 1 iterations or 1 steps MULLIKEN POPULATION ANALYSIS # Atom Element Kind Atomic population Net charge 1 C 1 3.733008 0.266992 2 O 2 6.308038 -0.308038 3 H 3 0.718305 0.281695 4 O 2 6.277961 -0.277961 5 O 2 6.233339 -0.233339 6 H 3 0.729348 0.270652 # Total charge 24.000000 0.000000 Electronic density on regular grids: -24.0000073560 -0.0000073560 Core density on regular grids: 24.0000000488 0.0000000488 Total charge density on r-space grids: -0.0000073072 Total charge density g-space grids: -0.0000073072 rank 0 in job 1 kamadhenu.intranet.jncasr.ac.in_36566 caused collective abort of all ranks exit status of rank 0: return code 174 forrtl: severe (174): SIGSEGV, segmentation fault occurred Image PC Routine Line Source cp2k.popt 00000000009EFBB7 Unknown Unknown Unknown cp2k.popt 00000000004CD495 Unknown Unknown Unknown cp2k.popt 000000000065D7C8 Unknown Unknown Unknown cp2k.popt 000000000065CB72 Unknown Unknown Unknown cp2k.popt 000000000040CDA6 Unknown Unknown Unknown cp2k.popt 000000000040B750 Unknown Unknown Unknown cp2k.popt 000000000040A50F Unknown Unknown Unknown cp2k.popt 00000000004092C2 Unknown Unknown Unknown libc.so.6 00000035FF01D8B4 Unknown Unknown Unknown cp2k.popt 00000000004091E9 Unknown Unknown Unknown Input file : &FORCE_EVAL METHOD Quickstep &DFT BASIS_SET_FILE_NAME BASIS_MOLOPT POTENTIAL_FILE_NAME POTENTIAL CHARGE = 0 &MGRID CUTOFF 200 NGRIDS 5 REL_CUTOFF 40 &END MGRID &QS METHOD GPW EPS_DEFAULT 1.0E-10 &END QS &SCF SCF_GUESS RESTART EPS_SCF 1.0E-5 MAX_SCF 1000 # MIXING 0.3 &OUTER_SCF EPS_SCF 1.0E-3 MAX_SCF 50 &END &OT MINIMIZER CG PRECONDITIONER FULL_ALL ENERGY_GAP 0.001 STEPSIZE 0.05 &END &END SCF &XC &XC_FUNCTIONAL BLYP &END XC_FUNCTIONAL &vdW_POTENTIAL DISPERSION_FUNCTIONAL PAIR_POTENTIAL &PAIR_POTENTIAL TYPE DFTD2 REFERENCE_FUNCTIONAL BLYP &END PAIR_POTENTIAL &END vdW_POTENTIAL &XC_GRID XC_SMOOTH_RHO NN50 XC_DERIV SPLINE2 &END &END XC &END DFT &SUBSYS &CELL ABC 10.0 10.0 10.0 PERIODIC NONE &END CELL &COORD @INCLUDE coor.xyz &END COORD &KIND O BASIS_SET TZV2P-MOLOPT-GTH-q6 POTENTIAL GTH-BLYP-q6 &END KIND &KIND C BASIS_SET TZV2P-MOLOPT-GTH-q4 POTENTIAL GTH-BLYP-q4 &END KIND &KIND H BASIS_SET TZV2P-MOLOPT-GTH-q1 POTENTIAL GTH-BLYP-q1 MASS 2.016 &END KIND &COLVAR &DISTANCE ATOMS 4 3 &END &PRINT &PROGRAM_RUN_INFO ON &EACH MD 1 &END &END PROGRAM_RUN_INFO &END PRINT &END &END SUBSYS &END FORCE_EVAL &GLOBAL PROJECT OUT-CA-AS RUN_TYPE MD PRINT_LEVEL MEDIUM &END GLOBAL &MOTION &CONSTRAINT &CONSTRAINT_INFO &EACH MD 1 &END &END &COLLECTIVE COLVAR 1 MOLECULE 1 TARGET 1.2 &RESTRAINT K [kcalmol] 10.0 &END &END &END &PRINT &VELOCITIES &EACH MD 1 &END &END &FORCES &EACH MD 1 &END &END &END &MD ENSEMBLE NVT STEPS 4000 TIMESTEP 0.5 TEMPERATURE 298.15 &THERMOSTAT TYPE CSVR &CSVR TIMECON [fs] 20. &END &END THERMOSTAT &END MD &END MOTION ----------------------- With out restraint option, MD is running with out any error. I tried many times changing options, but it didn't work. Can anybody help me ? Thanks in advance. Regards, Sandeep