In this exercise, you will perform geometry optimization using DFT. See GEO_OPT

Note the different RUN_TYPE and the changed PROJECT name. The latter is not strictly necessary but recommended since CP2K automatically creates additional files using this project name as a prefix.

H2O.inp

&GLOBAL
  PROJECT H2O
  RUN_TYPE GEO_OPT
  PRINT_LEVEL MEDIUM
&END GLOBAL

&MOTION
  &GEO_OPT
    MAX_ITER 3000
    OPTIMIZER BFGS    #Most efficient minimizer, but only for 'small' systems
  &END GEO_OPT
&END MOTION


&FORCE_EVAL
  METHOD Quickstep              ! Electronic structure method (DFT,...)
  &DFT
    BASIS_SET_FILE_NAME  BASIS_MOLOPT
    POTENTIAL_FILE_NAME  POTENTIAL

    &POISSON                    ! Solver requested for non periodic calculations
      PERIODIC NONE
      PSOLVER  WAVELET          ! Type of solver
    &END POISSON
    &SCF                        ! Parameters controlling the convergence of the scf. This section should not be changed. 
      SCF_GUESS ATOMIC
      EPS_SCF 1.0E-6
      MAX_SCF 300
    &END SCF
    &XC                        ! Parameters needed to compute the electronic exchange potential 
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
    &END XC
  &END DFT

  &SUBSYS
    &CELL
      ABC 10 10 10
      PERIODIC NONE              ! Non periodic calculations. That's why the POISSON section is needed 
    &END CELL
    &TOPOLOGY                    ! Section used to center the atomic coordinates in the given box. Useful for big molecules
      &CENTER_COORDINATES
      &END
      COORD_FILE_FORMAT xyz
      COORD_FILE_NAME  ./H2O.xyz
    &END
    &KIND H
      ELEMENT H
      BASIS_SET DZVP-MOLOPT-GTH
      POTENTIAL GTH-PBE-q1
    &END KIND
    &KIND O
      ELEMENT C
      BASIS_SET DZVP-MOLOPT-GTH
      POTENTIAL GTH-PBE-q6
    &END KIND
  &END SUBSYS
&END FORCE_EVAL

You can also directly open an XYZ file in VMD to visualize it:

$ vmd H2O.xyz

After running this, you will have the following files:

$ ls H2O*
H2O-1.restart        H2O-1.restart.bak-3  H2O.out          H2O-RESTART.wfn.bak-1
H2O-1.restart.bak-1  H2O-BFGS.Hessian     H2O-pos-1.xyz    H2O-RESTART.wfn.bak-2
H2O-1.restart.bak-2  H2O.inp              H2O-RESTART.wfn  H2O-RESTART.wfn.bak-3

Take a look at the output file, especially the following section (repeated the number of cycles it took to reach convergence):

 --------  Informations at step =     1 ------------
  Optimization Method        =                 BFGS
  Total Energy               =       -14.9417142787
  Real energy change         =        -0.1955604816
  Predicted change in energy =        -0.1885432833
  Scaling factor             =         0.0000000000
  Step size                  =         0.2677976891
  Trust radius               =         0.4724315332
  Decrease in energy         =                  YES
  Used time                  =               19.018

  Convergence check :
  Max. step size             =         0.2677976891
  Conv. limit for step size  =         0.0030000000
  Convergence in step size   =                   NO
  RMS step size              =         0.1458070233
  Conv. limit for RMS step   =         0.0015000000
  Convergence in RMS step    =                   NO
  Max. gradient              =         0.0287243359
  Conv. limit for gradients  =         0.0004500000
  Conv. for gradients        =                   NO
  RMS gradient               =         0.0180771987
  Conv. limit for RMS grad.  =         0.0003000000
  Conv. for gradients        =                   NO
 ---------------------------------------------------

For each convergence criterion, you see the value which is used to check whether convergence is reached and convergence is only reached if all of them are satisfied simultaneously.