QMMM: MM SPLINE: no convergence

[Peter]

Dear all,

I'm trying to setup qm/mm calculations of a test system. MM treatment
of a system using FIST works fine. However, QM/MM calculation fails
with the following message:

 *** 22:36:04 ERRORL2 in pair_potential:generate_spline_low
processor       ***
 *** 0  err=-300  SPLINE_INFO| Number of points:  2346797
obtained          ***
 *** accuracy 0.195114E-06. MM SPLINE: no convergence on required
accuracy  ***
 *** (adjust EPS_SPLINE and rerun) pair_potential.F line
551             ***

Adjusting EPS_SPLINE and/or R0_NB, EMAX_SPLINE solves the problem.
However I found this situation quite strange, since MM calculations
using the same FF and coordinates don't need such adjustments. Also
I've noticed, that during QMMM run spline generator uses much wider
boundaries (RMIN, RMAX) for some pairs, compared to MM run.

So, is it the supposed behavior of the program? And if so, could you
comment on it, please?

Thanks,
Peter

Input and log files: http://groups.google.com/group/cp2k/web/mm_spline-no_convergence.tar.gz

# u10-qmmm.inp:
&GLOBAL
  PROJECT U10-QMMM_OPT
  RUN_TYPE GEO_OPT
  PREFERRED_FFT_LIBRARY FFTMKL
&END GLOBAL

&MOTION
  &GEO_OPT
    TYPE MINIMIZATION
    MAX_ITER 10000
    OPTIMIZER LBFGS
    MAX_FORCE 5.0E-4
    RMS_FORCE 2.0E-4
    &LBFGS
      MAX_H_RANK 10
      MAX_F_PER_ITER 100
    &END LBFGS
  &END GEO_OPT

  &PRINT
    &RESTART OFF
    &END RESTART
    &RESTART_HISTORY OFF
    &END RESTART_HISTORY
    &TRAJECTORY
      FORMAT XYZ
      FILENAME =u10-qmmm.xyz
    &END TRAJECTORY
  &END PRINT
&END MOTION

&FORCE_EVAL
  METHOD QMMM

  &DFT
    CHARGE 0
    MULTIPLICITY 1
    BASIS_SET_FILE_NAME EMSL_BASIS_SETS
    POTENTIAL_FILE_NAME POTENTIAL

    &MGRID
      CUTOFF 250
      COMMENSURATE
    &END MGRID

    &QS
      METHOD GAPW
    &END QS

    &SCF
      SCF_GUESS ATOMIC
      EPS_SCF 1.0E-6
      MAX_SCF 150
    &END SCF

    &XC
#These are the coefficients used for B3LYP using VWN5, this is
recommended but doesn't match the default Gaussian definition
      &XC_FUNCTIONAL
       &LYP
         SCALE_C 0.81
       &END
       &BECKE88
         SCALE_X 0.72
       &END
       &VWN
         FUNCTIONAL_TYPE VWN5
         SCALE_C 0.19
       &END
       &XALPHA
         SCALE_X 0.08
       &END
      &END XC_FUNCTIONAL
      &HF
        &SCREENING
          EPS_SCHWARZ 1.0E-10
        &END
        &MEMORY
          MAX_MEMORY  5
        &END
        FRACTION 0.20
      &END
    &END XC

    &POISSON
      PERIODIC NONE
      POISSON_SOLVER WAVELET
    &END POISSON
  &END DFT


  &MM
    &FORCEFIELD
      PARM_FILE_NAME par_all27_prot_lipid.prm
      PARMTYPE CHM
      &SPLINE
        RCUT_NB 50.0
#        UNIQUE_SPLINE T
#        EPS_SPLINE 1.0E-12
#        EMAX_SPLINE 0.02
#        R0_NB = 0.45
      &END SPLINE
    &END FORCEFIELD

    &POISSON
      PERIODIC NONE
      &EWALD
        EWALD_TYPE NONE
      &END EWALD
    &END POISSON

    &NEIGHBOR_LISTS
      GEO_CHECK F
    &END NEIGHBOR_LISTS

    &PRINT
      &FF_INFO
      &END FF_INFO
    &END PRINT
  &END MM

  &QMMM
    &CELL
      ABC 15.0 15.0 15.0
    &END CELL

    &QM_KIND H
      MM_INDEX 14 15 16 17 18 19 20 21 22 28 29
    &END QM_KIND

    &QM_KIND C
      MM_INDEX 1 2 3 4 5 6 7 8 9 23
    &END QM_KIND

    &QM_KIND O
      MM_INDEX 10 11 12 13
    &END QM_KIND

    &LINK
      QM_INDEX 23
      MM_INDEX 24
      QM_KIND H
    &END LINK

  &END QMMM

  &SUBSYS
    &CELL
      ABC 50.0 50.0 50.0
      PERIODIC NONE
    &END CELL

    &TOPOLOGY
      COORD_FILE_NAME u10.pdb
      COORD_FILE_FORMAT PDB
      CONN_FILE_NAME u10.psf
      CONN_FILE_FORMAT PSF
      CENTER_COORDINATES
    &END TOPOLOGY

    &KIND O
      BASIS_SET 6-31G*
      POTENTIAL ALL
    &END KIND

    &KIND C
      BASIS_SET 6-31G*
      POTENTIAL ALL
    &END KIND

    &KIND H
      BASIS_SET 6-31G*
      POTENTIAL ALL
    &END KIND
  &END SUBSYS
&END FORCE_EVAL