<div dir="ltr">I am attempting to run a geometry optimization on MgSi2O3 using a Buckingham potential.  I attempted to include a three-body interaction among the Si-O, but it does not appear to have any effect at all on the outcome.  I've attempted to adjust the force constant, but no difference in final result.  Am I missing the meaning of this section?<div><br></div><div>Furthermore, I would like to (for testing purposes) eliminate the Mg-Si electrostatic interaction, but am unsure how to do this.  Is there a way to exclude this interaction?</div><div><br></div><div>Thanks.</div><div><br></div><div>-Christopher Mauney</div><div><br></div><div>input file:</div><div><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"> &GLOBAL<br>   BLACS_GRID  SQUARE<br>   BLACS_REPEATABLE  F<br>   PREFERRED_DIAG_LIBRARY  SL<br>   PREFERRED_FFT_LIBRARY  FFTW3<br>   FFTW_WISDOM_FILE_NAME /etc/fftw/wisdom<br>   FFTW_PLAN_TYPE  ESTIMATE<br>   EXTENDED_FFT_LENGTHS  F<br>   FFT_POOL_SCRATCH_LIMIT  15<br>   ALLTOALL_SGL  F<br>   PRINT_LEVEL  LOW<br>   PROGRAM_NAME  CP2K<br>   PROJECT_NAME sigen-test<br>   OUTPUT_FILE_NAME <br>   RUN_TYPE  GEO_OPT<br>   WALLTIME <br>   ECHO_INPUT  F<br>   ECHO_ALL_HOSTS  F<br>   TRACE  F<br>   TRACE_MASTER  T<br>   TRACE_MAX  2147483647<br>   FLUSH_SHOULD_FLUSH  T<br>   CALLGRAPH  NONE<br>   CALLGRAPH_FILE_NAME <br>   SEED  2000<br>   SAVE_MEM  F<br>   ENABLE_UNSUPPORTED_FEATURES  F<br> &END GLOBAL<br> &MOTION<br>   &GEO_OPT<br>     TYPE  MINIMIZATION<br>     OPTIMIZER  BFGS<br>     MAX_ITER  100<br>     MAX_DR     1.0000000000000000E-04<br>     MAX_FORCE     1.0000000000000001E-05<br>     RMS_DR     1.5000000000000000E-03<br>     RMS_FORCE     2.9999999999999997E-04<br>     STEP_START_VAL  0<br>     &BFGS<br>       TRUST_RADIUS     2.5000000000000000E-01<br>       USE_MODEL_HESSIAN  T<br>       USE_RAT_FUN_OPT  F<br>       RESTART_HESSIAN  F<br>       RESTART_FILE_NAME <br>       &RESTART  OFF<br>         ADD_LAST  NUMERIC<br>         COMMON_ITERATION_LEVELS  2<br>         FILENAME BFGS<br>         LOG_PRINT_KEY  F<br>       &END RESTART<br>     &END BFGS<br>   &END GEO_OPT<br>   &PRINT<br>     &TRAJECTORY  SILENT<br>       ADD_LAST  NUMERIC<br>       COMMON_ITERATION_LEVELS  1<br>       FILENAME <br>       LOG_PRINT_KEY  F<br>       UNIT angstrom<br>       FORMAT  XMOL<br>       CHARGE_OCCUP  F<br>       CHARGE_BETA  F<br>       CHARGE_EXTENDED  F<br>       &EACH<br>         JUST_ENERGY  1<br>         POWELL_OPT  1<br>         QS_SCF  1<br>         XAS_SCF  1<br>         MD  1<br>         METADYNAMICS  1<br>         GEO_OPT  1<br>         ROT_OPT  1<br>         CELL_OPT  1<br>         BAND  1<br>         EP_LIN_SOLVER  1<br>         SPLINE_FIND_COEFFS  1<br>         REPLICA_EVAL  1<br>         BSSE  1<br>         SHELL_OPT  1<br>       &END EACH<br>     &END TRAJECTORY<br>     &RESTART  OFF<br>       ADD_LAST  NUMERIC<br>       COMMON_ITERATION_LEVELS  1<br>       FILENAME <br>       LOG_PRINT_KEY  F<br>       BACKUP_COPIES  3<br>       SPLIT_RESTART_FILE  F<br>     &END RESTART<br>     &RESTART_HISTORY  OFF<br>       ADD_LAST  NO<br>       COMMON_ITERATION_LEVELS  0<br>       FILENAME <br>       LOG_PRINT_KEY  F<br>     &END RESTART_HISTORY<br>   &END PRINT<br> &END MOTION<br> &FORCE_EVAL<br>   METHOD  FIST<br>   STRESS_TENSOR  NONE<br>   &MM<br>     &FORCEFIELD<br>       PARMTYPE  OFF<br>       VDW_SCALE14     1.0000000000000000E+00<br>       EI_SCALE14     0.0000000000000000E+00<br>       SHIFT_CUTOFF  T<br>       DO_NONBONDED  T<br>       IGNORE_MISSING_CRITICAL_PARAMS  F<br>       MULTIPLE_POTENTIAL  F<br>       ZBL_SCATTERING  F<br>       &SPLINE<br>         R0_NB     1.0000000000000001E-01<br>         RCUT_NB    -1.0000000000000000E+00<br>         EMAX_SPLINE     1.0000000000000000E+02<br>         EMAX_ACCURACY     2.0000000000000000E-02<br>         EPS_SPLINE     9.9999999999999995E-08<br>         NPOINTS  -1<br>         UNIQUE_SPLINE  F<br>       &END SPLINE<br>       &NONBONDED<br>         &WILLIAMS<br>           ATOMS O O<br>           A     2.6416495841429514E+08<br>           B     6.7114093959731544E+00<br>           C     3.2353360747630242E+05<br>           RCUT     1.0000000000000002E+01<br>         &END WILLIAMS<br>         &WILLIAMS<br>           ATOMS Si O<br>           A     1.4899105572958285E+07<br>           B     3.1199301135654558E+00<br>           C     1.2372236150635568E+05<br>           RCUT     1.0000000000000002E+01<br>         &END WILLIAMS<br>         &WILLIAMS<br>           ATOMS Si Si<br>           A     9.2258269084930563E+08<br>           B     4.9751243781094523E+00<br>           C     5.1846608733236147E+06<br>           RCUT     1.0000000000000002E+01<br>         &END WILLIAMS<br>         &WILLIAMS<br>           ATOMS Mg O<br>           A     9.5342615460017957E+06<br>           B     3.0845157310302285E+00<br>           C     0.0000000000000000E+00<br>           RCUT     1.0000000000000002E+01<br>         &END WILLIAMS<br>         &WILLIAMS<br>           ATOMS Mg Si<br>           A     0.0000000000000000E+00<br>           B     0.0000000000000000E+00<br>           C     0.0000000000000000E+00<br>           RCUT     1.0000000000000002E+01<br>         &END WILLIAMS<br>         &WILLIAMS<br>           ATOMS Mg Mg<br>           A     0.0000000000000000E+00<br>           B     0.0000000000000000E+00<br>           C     0.0000000000000000E+00<br>           RCUT     1.0000000000000002E+01<br>         &END WILLIAMS<br>       &END NONBONDED<br>       &CHARGE<br>         ATOM O<br>         CHARGE    -2.0000000000000000E+00<br>       &END CHARGE<br>       &CHARGE<br>         ATOM SI<br>         CHARGE     4.0000000000000000E+00<br>       &END CHARGE<br>       &CHARGE<br>         ATOM MG<br>         CHARGE     2.0000000000000000E+00<br>       &END CHARGE<br>       &BEND<br>         ATOMS O SI O<br>         KIND  HARMONIC<br>         K     2.0972000000000000E+00<br>         CB     0.0000000000000000E+00<br>         R012     0.0000000000000000E+00<br>         R032     0.0000000000000000E+00<br>         KBS12     0.0000000000000000E+00<br>         KBS32     0.0000000000000000E+00<br>         KSS     0.0000000000000000E+00<br>         THETA0     1.9106119321581925E+00<br>       &END BEND<br>       &BEND<br>         ATOMS O MG O<br>         KIND  HARMONIC<br>         K     2.0972000000000000E+00<br>         CB     0.0000000000000000E+00<br>         R012     0.0000000000000000E+00<br>         R032     0.0000000000000000E+00<br>         KBS12     0.0000000000000000E+00<br>         KBS32     0.0000000000000000E+00<br>         KSS     0.0000000000000000E+00<br>         THETA0     1.5707963267948966E+00<br>       &END BEND<br>     &END FORCEFIELD<br>     &POISSON<br>       POISSON_SOLVER  ANALYTIC<br>       PERIODIC  NONE<br>       &EWALD<br>         EWALD_TYPE  NONE<br>         EWALD_ACCURACY     9.9999999999999995E-07<br>         ALPHA     3.4999999999999998E-01<br>         NS_MAX  11<br>         O_SPLINE  6<br>         EPSILON     9.9999999999999995E-07<br>       &END EWALD<br>     &END POISSON<br>   &END MM<br>   &SUBSYS<br>     &CELL<br>       ABC     2.0000000000000004E+01    2.0000000000000004E+01    2.0000000000000004E+01<br>       ALPHA_BETA_GAMMA     9.0000000000000000E+01    9.0000000000000000E+01    9.0000000000000000E+01<br>       CELL_FILE_FORMAT  CP2K<br>       PERIODIC  NONE<br>       MULTIPLE_UNIT_CELL  1 1 1<br>       SYMMETRY  NONE<br>     &END CELL<br>     &TOPOLOGY<br>       CHARGE_OCCUP  F<br>       CHARGE_BETA  F<br>       CHARGE_EXTENDED  F<br>       PARA_RES  T<br>       MOL_CHECK  T<br>       USE_G96_VELOCITY  F<br>       COORD_FILE_NAME mgsi-test.xyz<br>       COORD_FILE_FORMAT  XYZ<br>       NUMBER_OF_ATOMS  -1<br>       CONN_FILE_FORMAT  GENERATE<br>       DISABLE_EXCLUSION_LISTS  F<br>       EXCLUDE_VDW  1-3<br>       EXCLUDE_EI  1-3<br>       AUTOGEN_EXCLUDE_LISTS  F<br>       MULTIPLE_UNIT_CELL  1 1 1<br>       MEMORY_PROGRESSION_FACTOR     1.2000000000000000E+00<br>     &END TOPOLOGY<br>   &END SUBSYS<br> &END FORCE_EVAL</blockquote></div><div><br></div><div>mgsi-test.xyz:</div><div><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;">6</blockquote><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"> </blockquote><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;">Si       5.100733801   7.021427036   5.000000000<br>Si       8.599266199   7.021427036   5.000000000<br>O        6.850000000   7.149878576   5.000000000<br>O        5.000213137   5.388401447   5.000000000<br>O        8.699786863   5.388401447   5.000000000<br>Mg       6.850000000   5.000464458   5.000000000</blockquote></div><div><br></div></div>