Bad convergence performance for the MXene system

[zhouk...@gmail.com]

Dear all,

Now I am simulation the MXene (Ti3C2O2)+water system.  But SCF can not converge. 

The initial structure is from the MD simulation using VASP (PBE+D3) and thus the problem is not from bad positions of atoms.

Can anyone give me some suggestions?

Best,

Justin

-----------------------------------------------------------------

&FORCE_EVAL
  ! the electronic structure part of CP2K is named Quickstep
  METHOD Quickstep
  STRESS_TENSOR ANALYTICAL
  &DFT
    BASIS_SET_FILE_NAME   ./BASIS_MOLOPT  
    POTENTIAL_FILE_NAME   ./POTENTIAL
    WFN_RESTART_FILE_NAME ./MX-RESTART.wfn
    &MGRID
       CUTOFF [Ry] 400
    &END
    &QS
       ! use the GPW method (i.e. pseudopotential based calculations with the Gaussian and Plane Waves scheme).
       METHOD GPW
       ! default threshold for numerics ~ roughly numerical accuracy of the total energy per electron,
       ! sets reasonable values for all other thresholds.
       EPS_DEFAULT 1.0E-10
       ! used for MD, the method used to generate the initial guess.
       EXTRAPOLATION ASPC
       EXTRAPOLATION_ORDER 4
    &END

    &POISSON
       PERIODIC XYZ ! the default, gas phase systems should have 'NONE' and a wavelet solver
    &END
    &PRINT
     ! output atomic charge
     &MULLIKEN
       ! FILENAME ${SYSTEM}
       &EACH
            MD 10
       &END EACH
     &END MULLIKEN
     ! output others
    &END
    ! use the OT METHOD for robust and efficient SCF, suitable for all non-metallic systems.
    &SCF                              
      SCF_GUESS RESTART !!!#####ATOMIC ! can be used to RESTART an interrupted calculation
      MAX_SCF 1000
      EPS_SCF 1.0E-7
      &OUTER_SCF ! repeat the inner SCF cycle 10 times
        MAX_SCF 10
        EPS_SCF 1.0E-7
      &END

      &OT ON
        MINIMIZER DIIS
      &END OT



    &END SCF

    ! specify the exchange and correlation treatment
    &XC
      ! use a PBE functional
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
      ! adding Grimme's D3 correction (by default without C9 terms)
      &VDW_POTENTIAL
         POTENTIAL_TYPE PAIR_POTENTIAL
         &PAIR_POTENTIAL
            PARAMETER_FILE_NAME dftd3.dat
            TYPE DFTD3
            REFERENCE_FUNCTIONAL PBE
         &END
      &END VDW_POTENTIAL

      &XC_GRID
         XC_SMOOTH_RHO NN50
         XC_DERIV NN50_SMOOTH
      &END

    &END XC
  &END DFT

 
  ! description of the system
  &SUBSYS
    &CELL
      ! unit cells that are orthorhombic are more efficient with CP2K
      ABC [angstrom] 12.0944890976000003 10.4741353988999997 16.2000007629000002
    &END CELL

    ! atom coordinates can be in the &COORD section,
    ! or provided as an external file.
    &TOPOLOGY
      COORD_FILE_NAME MX-wt.xyz
      COORD_FILE_FORMAT XYZ
    &END

    ! MOLOPT basis sets are fairly costly,
    ! but in the 'DZVP-MOLOPT-SR-GTH' available for all elements
    ! their contracted nature makes them suitable
    ! for condensed and gas phase systems alike.

    &KIND C
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-PBE
    &END KIND
    &KIND Ti
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-PBE
    &END KIND
    &KIND H
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-PBE
    &END KIND
    &KIND O
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-PBE
    &END KIND
    &KIND Li
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-PBE
    &END KIND
  &END SUBSYS
&END FORCE_EVAL

-----------------------

[zhouk...@gmail.com]

Here is the input and structure file.

[Thomas Kühne]

Dear Justin, 

please sent the output, i.e. in particular during the OT loop for better assistance. 

Typical, hints may be: 

(i) set EPS_DEFAULT to 1.0E-12

(ii) reduce MAX_SCF in the inner OT loop to s.th. more reasonable than 40-50. 

(iii) reduce stepsize to 0.1 or lower

(iv) use different PRECONDITIONER such as FULL_ALL to together with 

ENERGY_GAP 0.0001

(v) use CG instead of DIIS 

Best, 

Thomas Kühne

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<eq.inp><MX-wt.xyz>

==============================

Thomas D. Kühne

Dynamics of Condensed Matter

Chair of Theoretical Chemistry

University of Paderborn

Warburger Str. 100

D-33098 Paderborn

Germany

thomas...@upb.de

+49/(0)5251/60-5726