[CP2K-user] strange curve of the binding energy of Na-Cl

[mejdeddine mokhtar]

Dear CP2K developers and users,

I've tried to compute the binding energy of Na _ Cl (singlet state so the 
Multiplicity should be 1)but I got a strange curve at large distances. I 
don't have a lot o experience in using cp2k so I attached the script that 
I've used to calculate the potential energy at varying distance. Could 
someone check if I did something wrong? any help would be appreciated. 

&GLOBAL
    PROJECT NaCl
    RUN_TYPE ENERGY             
&END GLOBAL

&FORCE_EVAL

  METHOD Quickstep
  &DFT
      BASIS_SET_FILE_NAME BASIS_MOLOPT
      POTENTIAL_FILE_NAME GTH_POTENTIALS            
      CHARGE 0
      MULTIPLICITY 1

    &MGRID
       CUTOFF [Ry] 400 
    &END

    &QS
       METHOD GPW 
       EPS_DEFAULT 1.0E-6 
    &END

    &POISSON                      # POISSON solver for non-periodic 
calculation
       PERIODIC NONE
       PSOLVER WAVELET
    &END
    &SCF                              
      SCF_GUESS ATOMIC ! can be used to RESTART an interrupted calculation
      MAX_SCF 300
      EPS_SCF 1.0E-6 ! accuracy of the SCF procedure typically 1.0E-6 - 
1.0E-7
      &OT
        PRECONDITIONER FULL_SINGLE_INVERSE
        MINIMIZER DIIS
      &END OT
      &MIXING
         METHOD BROYDEN_MIXING
         ALPHA  0.4
         BETA   1.5
         NBROYDEN 8
      &END MIXING
      &OUTER_SCF ! repeat the inner SCF cycle 10 times
        MAX_SCF 100
        EPS_SCF 1.0E-5 ! must match the above
        OPTIMIZER  DIIS
      &END
    &END SCF
    &XC
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL 
    &END XC
  &END DFT
   &SUBSYS
    &CELL 
      ABC [angstrom] 10.00 10.00 10.00
    &END CELL
    &COORD
Na    0.0 0.0 0.0 
Cl    0.0 0.0 MYDIST
    &END COORD
    &TOPOLOGY
      CONNECTIVITY GENERATE
      &GENERATE
        BONDLENGTH_MAX 9
      &END
    &END
    &KIND Na                              
      BASIS_SET DZVP-MOLOPT-SR-GTH         
      POTENTIAL GTH-PBE          
    &END KIND
    &KIND Cl
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-PBE
    &END KIND
  &END SUBSYS
&END FORCE_EVAL


The bash script used to get the calculation running is the following: 

rm -f ener_profile

#for dist in `seq 2.3 0.1 6.0`
for dist in 4.0 5.0 6.0 7.0 8.0 10.0; do

  #
  # compute energy 
  # 
  echo "Computing potential energy for distance $dist"
  sed "s/MYDIST/${dist}/g" mode1.inp > inp
  cp2k.popt inp > out 
  ener=`grep ' ENERGY| Total FORCE_EVAL' out | awk '{print $NF}'`
  echo $dist $ener >> ener_profile

done

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20200706/ce08e860/attachment.htm>