Iron surface

marcello rosini.... at gmail.com
Tue Mar 8 17:28:58 CET 2011


Hallo everybody...
I am new to cp2k so forgive if I my questions may sound silly...
After some succesfull calculations on smaller systems I am trying to
setup the simulation of a Fe surface, but my calculation does not
converge. Actually the scf cycle does not converge

Q1- The basis for Fe is the only one I found on the CP2k source
tree... is it correct to mix PADE basis with PBE potential and XC?
Q2- Are the parameters controlling the scf correct? I cannot manage
them to obtain convergence...
Q3- is the dimension of the surface too small for a metal?
Q4- does anyone have some suggestion/basis-set/potential for my
system?

Thanks in advance to everybody
Marcello

----------------
this is my input:

&GLOBAL
  RUN_TYPE GEO_OPT
&END GLOBAL
!
&FORCE_EVAL
  METHOD Quickstep
  &DFT
    BASIS_SET_FILE_NAME MIOBASIS
    POTENTIAL_FILE_NAME MIOPOT
    LSD
    &MGRID
      CUTOFF 240
    &END MGRID
    &QS
      EPS_DEFAULT 1.0E-14
      EXTRAPOLATION PS
    &END QS
    &SCF
      EPS_SCF 4.0E-7
      SCF_GUESS atomic
      MAX_SCF 500
      CHOLESKY INVERSE
      ADDED_MOS 120 120
      &DIAGONALIZATION on
        ALGORITHM standard
      &END DIAGONALIZATION
      &MIXING on
        METHOD broyden_mixing
        ALPHA 0.05
        BETA 1.5
        NBROYDEN 8
      &END MIXING
      &SMEAR on
         METHOD energy_window
         WINDOW_SIZE [Ry] 0.02
      &END SMEAR
    &END SCF
    &XC
      &XC_FUNCTIONAL pbe
      &END XC_FUNCTIONAL
    &END XC
  &END DFT
  &SUBSYS
    &CELL
      A 8.06666835 -5.70399589   0.0
      B 8.06666835  5.70399589   0.0
      C 0.0         0.0         28.23
      PERIODIC XYZ
    &END CELL
    &COORD
   Fe   12.10000000   -0.00000315    8.05240000
   Fe   10.08330000    1.42600000    8.05240000
   Fe   10.08330000   -1.42600000    8.05240000
   Fe    8.06667000    0.00000088    8.05240000
   Fe    8.06667000   -2.85200000    8.05240000
   Fe    8.06667000    2.85199000    8.05240000
   Fe    6.05000000    4.27800000    8.05240000
   Fe    6.05000000   -4.27800000    8.05240000
   Fe    6.05000000    1.42600000    8.05240000
   Fe    6.05000000   -1.42600000    8.05240000
   Fe    4.03333000   -0.00000158    8.05240000
   Fe    4.03333000    2.85200000    8.05240000
   Fe    4.03333000   -2.85200000    8.05240000
   Fe    2.01667000    1.42600000    8.05240000
   Fe    2.01667000   -1.42600000    8.05240000
   Fe    0.00000000    0.00000000    8.05240000
   Fe   14.11670000   -0.00000315    6.05311000
   Fe   12.10000000    1.42600000    6.05311000
   Fe   12.10000000   -1.42600000    6.05311000
   Fe   10.08330000    0.00000088    6.05311000
   Fe   10.08330000   -2.85200000    6.05311000
   Fe   10.08330000    2.85199000    6.05311000
   Fe    8.06667000    4.27800000    6.05311000
   Fe    8.06667000   -4.27800000    6.05311000
   Fe    8.06667000    1.42600000    6.05311000
   Fe    8.06667000   -1.42600000    6.05311000
   Fe    6.05000000   -0.00000158    6.05311000
   Fe    6.05000000    2.85200000    6.05311000
   Fe    6.05000000   -2.85200000    6.05311000
   Fe    4.03333000    1.42600000    6.05311000
   Fe    4.03333000   -1.42600000    6.05311000
   Fe    2.01667000    0.00000000    6.05311000
   Fe   12.10000000   -0.00000315    4.03452000   BOT
   Fe   10.08330000    1.42600000    4.03452000   BOT
   Fe   10.08330000   -1.42600000    4.03452000   BOT
   Fe    8.06667000    0.00000088    4.03452000   BOT
   Fe    8.06667000   -2.85200000    4.03452000   BOT
   Fe    8.06667000    2.85199000    4.03452000   BOT
   Fe    6.05000000    4.27800000    4.03452000   BOT
   Fe    6.05000000   -4.27800000    4.03452000   BOT
   Fe    6.05000000    1.42600000    4.03452000   BOT
   Fe    6.05000000   -1.42600000    4.03452000   BOT
   Fe    4.03333000   -0.00000158    4.03452000   BOT
   Fe    4.03333000    2.85200000    4.03452000   BOT
   Fe    4.03333000   -2.85200000    4.03452000   BOT
   Fe    2.01667000    1.42600000    4.03452000   BOT
   Fe    2.01667000   -1.42600000    4.03452000   BOT
   Fe    0.00000000    0.00000000    4.03452000   BOT
    &END COORD
    &KIND Fe
      BASIS_SET DZV-GTH-PADE
      POTENTIAL GTH-PBE-q16
    &END KIND
  &END SUBSYS
&END FORCE_EVAL
!
&MOTION
  &GEO_OPT
    OPTIMIZER BFGS
    MAX_ITER 200
  &END GEO_OPT
  &CONSTRAINT
    &FIXED_ATOMS
      COMPONENTS_TO_FIX XYZ
      MOLNAME BOT
    &END FIXED_ATOMS
  &END CONSTRAINT
&END MOTION


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