The warning in the MD calculation

[jian...@gmail.com]

Dear cp2k users,

When I do a MD simulation, there are two warning in each SCF calculation?

Could you give me some advice?

 ===== Routine Calling Stack ===== 

            8 set_mo_occupation_1

            7 set_mo_occupation_2

            6 scf_env_do_scf_inner_loop

            5 scf_env_do_scf

            4 qs_energies_scf

            3 qs_forces

            2 qs_mol_dyn_low

            1 CP2K

 *** 19:54:49 WARNING in qs_mo_occupation:set_mo_occupation_1 :: ***

 *** Fermi-Dirac smearing includes the first MO                  ***

 *** 19:54:49 WARNING in qs_mo_occupation:set_mo_occupation_1 ::          ***

 *** Fermi-Dirac smearing includes the last MO => Add more MOs for proper ***

 *** smearing.                                                            ***

The input file 

##########################################

&GLOBAL

  PROJECT 64Ar-MD

  RUN_TYPE MD

  PRINT_LEVEL LOW

&END GLOBAL

&MOTION

  &MD

    ENSEMBLE NVT

    STEPS 10000

    TIMESTEP 0.5

    TEMPERATURE 17200

    &THERMOSTAT

       REGION GLOBAL

       TYPE NOSE

       &NOSE

         LENGTH 3

         TIMECON 1.0

       &END

    &END

  &END MD

  &PRINT

    &STRESS SILENT

    &END STRESS

  &END PRINT

&END MOTION

&FORCE_EVAL

  METHOD Quickstep

  STRESS_TENSOR ANALYTICAL 

  &DFT

    BASIS_SET_FILE_NAME /home/myu1410/work/cp2k/261/cp2k-2.6.1/data/BASIS_SET

    POTENTIAL_FILE_NAME /home/myu1410/work/cp2k/261/cp2k-2.6.1/data/POTENTIAL

    MULTIPLICITY 1

    &MGRID

      CUTOFF 400

      NGRIDS 4

      REL_CUTOFF 30

    &END MGRID

    &QS

      EPS_DEFAULT 1.0E-12

      EPS_GVG 1.0E-6

      EPS_PGF_ORB 1.0E-6

      MAP_CONSISTENT

    &END QS

    &SCF

      MAX_SCF 200

      SCF_GUESS atomic

      EPS_SCF 1.00E-04

      CHOLESKY INVERSE

      &DIAGONALIZATION

      &END DIAGONALIZATION

#      &OT

#      &END OT

      ADDED_MOS 100 100

      &SMEAR

        ELECTRONIC_TEMPERATURE 17200

        METHOD FERMI_DIRAC

      &END SMEAR

      &MIXING

        METHOD BROYDEN_MIXING

        ALPHA 0.6

        BETA 1.0

        NBROYDEN 15

      &END

    &END SCF

    &XC

      &XC_GRID

        XC_SMOOTH_RHO NN10

        XC_DERIV SPLINE2

      &END XC_GRID

      &XC_FUNCTIONAL Pade

      &END XC_FUNCTIONAL

    &END XC

  &END DFT

  &SUBSYS

    &CELL

      ABC 13.00535 13.00535 13.00535

    &END CELL

    &COORD

     SCALED

     @INCLUDE './64ar.xyz0'

    &END COORD                                              

    &KIND Ar                   

      BASIS_SET DZVP-GTH-PADE    

      POTENTIAL GTH-PADE-q8     

    &END KIND                   

  &END SUBSYS                   

&END FORCE_EVAL 

##########################################

Thanks!

[Marcella Iannuzzi]

Hi jianzhifu,

Those warnings tell you that the Fermi-Dirac  smearing involves all the molecular orbitals, from the lowest to the highest in energy, 

which should not be the case. The Smearing should be applied only within a limited range of energies around the Fermi energy.

However, this behaviour is not surprising, since the electronic temperature, which determines the broadening of the smearing,  is set larger than 17000 Kelvin in your input.  

By the way, also the temperature of the atomic system is set at the same value, are you sure that you want to run MD at this temperature?

Regards

Marcella

[jian...@gmail.com]

Dear Marcella,

Thanks for your reply!

Yes, I need the thermal electron temperature is equal to the atom temperature, because I simulate the argon system in the high temperature and high density range. The argon atom will gradually be ionized and the system become plasma. I hope the system reach thermodynamic equilibrium. 

 

I have done the same thing by VASP code, but the calculation using VASP need more time. So I want to use CP2K do this simulation.

 

Here is vasp INCAR

##########################################

  SYSTEM = 64Ar-1.93g-17200k

PREC=Accurate

  ENCUT = 600.0

  IBRION = 0

  ISTART = 0

  IALGO = 48

  NSW = 10000

  NBLOCK = 1; KBLOCK = 50

  ISYM = 0

  SMASS = 1

  POTIM = 1.0

  TEBEG = 17200  #temperature

  TEEND = 17200

  ISMEAR = -1; SIGMA = 1.48218 #unit eV 1.48218 eV=17200 Kelvin

  LREAL = A

  ISIF = 2

  NELMIN = 6

  NBANDS = 500

##########################################

ISMEAR determines how the partial occupancies are set for each orbital. For the finite temperature LDA SIGMA determines the width of the smearing in eV.

ISMEAR=-1 is Fermi smearing.

 

I think the keyword of CP2K (SMEAR and ELECTRONIC_TEMPERTURE) have the same meanings.

 

Is that right about my understanding?

 

Best wishes,

jianzhifu