Hi, In my continuing saga of using cp2k for running qm/mm calculations I have encounter yet another bump. While using the input below I get this error "FORCEFIELD| Missing Bond ( CT, HC)" and angle ... &GLOBAL PROJECT mebox_qmmm RUN_TYPE MD PRINT_LEVEL LOW &END GLOBAL &MOTION &MD ENSEMBLE NVT STEPS 1000 TIMESTEP 1.0 TEMPERATURE 298 &THERMOSTAT REGION GLOBAL TYPE CSVR &CSVR TIMECON 100 &END CSVR &END THERMOSTAT &END MD &PRINT &RESTART OFF &END RESTART &RESTART_HISTORY OFF &END RESTART_HISTORY &END PRINT &END MOTION &FORCE_EVAL METHOD QMMM &DFT CHARGE 0 BASIS_SET_FILE_NAME GTH_BASIS_SETS POTENTIAL_FILE_NAME GTH_POTENTIALS &MGRID CUTOFF 280 COMMENSURATE &END MGRID &SCF MAX_SCF 20 EPS_SCF 1.0E-6 &OT T PRECONDITIONER FULL_ALL MINIMIZER DIIS &END OT &PRINT &RESTART OFF &END RESTART &RESTART_HISTORY OFF &END RESTART_HISTORY &END PRINT &END SCF &QS EPS_DEFAULT 1.0E-12 MAP_CONSISTENT EXTRAPOLATION ASPC EXTRAPOLATION_ORDER 3 &END QS &XC &XC_GRID XC_SMOOTH_RHO NN10 XC_DERIV NN10_SMOOTH &END XC_GRID &XC_FUNCTIONAL BLYP &END XC_FUNCTIONAL &END XC &POISSON POISSON_SOLVER MULTIPOLE PERIODIC NONE &END POISSON &END DFT &MM &FORCEFIELD VDW_SCALE14 0.5 EI_SCALE14 0.8333333 SCALE_CUTOFF .FALSE. PARM_FILE_NAME mebox.prmtop PARMTYPE AMBER &SPLINE EMAX_SPLINE 1.0 RCUT_NB 10 &END &END FORCEFIELD &POISSON &EWALD EWALD_TYPE SPME ALPHA .36 GMAX 23 23 23 &END EWALD &END POISSON &END MM &QMMM E_COUPL GAUSS USE_GEEP_LIB 7 &CELL ABC 8.0 8.0 8.0 PERIODIC NONE &END CELL &QM_KIND C MM_INDEX 1 &END QM_KIND &QM_KIND H MM_INDEX 2 3 4 5 &END QM_KIND &END QMMM &SUBSYS &CELL ABC [angstrom] 23.2782522 22.7141099 23.2326917 PERIODIC XYZ &END CELL &TOPOLOGY COORDINATE PDB COORD_FILE_NAME mebox_npt.pdb CONNECTIVITY AMBER CONN_FILE_NAME mebox.prmtop &END &KIND C BASIS_SET DZVP-GTH POTENTIAL GTH-BLYP-q4 &END KIND &KIND H BASIS_SET DZVP-GTH POTENTIAL GTH-BLYP-q1 &END KIND &END SUBSYS &END FORCE_EVAL If I change QMMM with FIST the input runs. I also have some additional questions, but on somewhat different matters. In the latest papers that I could find that use cp2k to do qm/mm calculations (<a href="http://dx.doi.org/10.1021/ja076081h">http://dx.doi.org/10.1021/ja076081h</a> and <a href="http://dx.doi.org/10.1021/jp074858n">http://dx.doi.org/10.1021/jp074858n</a>) the authors used a integration step of 0.5 and 0.48. Unfortunately, they did not discussed their choice. I'm used to running qm/mm md with other packages, but I've always used an integration step of 1 fs. Is cp2k different :-)? Is there any place where I can find information regarding the parameters xc_deriv and xc_smooth_rho and are "good" choices? Thanks, Marius