convergence of the electronic wavefunction for metal surface

[Matthias Krack]

Hi ?,

you request a smearing based on a Fermi-Dirac distribution, but you
didn't specify any electronic temperature for it. Thus you rely on the
default value of 300K for the electronic temperature which might be
too small. Note, the keyword WINDOW_SIZE should be used with the
method ENERGY_WINDOW. This might be at least one issue to improve the
convergence.

Matthias

On Dec 1, 12:09 pm, ires <inga.re... at uni-ulm.de> wrote:
> Hi,
>
> maybe someone can help me with this: I'm trying to perform a geometry
> optimization of C2H2 on Cu(100), and I can't get the electronic SCF to
> convergence without using OT (with OT it's no problem, but since it is
> a metallic surface, I thought it's better not to use OT?)
> I tried adding MOs and also smearing - here is one of the inputs I
> used:
>
> &FORCE_EVAL
>   METHOD Quickstep
>   &DFT
>     BASIS_SET_FILE_NAME  /users/depart1/irespond/cp2k/BASIS_MOLOPT
>     POTENTIAL_FILE_NAME /users/depart1/irespond/cp2k/GTH_POTENTIALS
> #   RESTART_FILE_NAME ./cuc2h2_pbe-RESTART.wfn
>     &MGRID
>       CUTOFF 600
>     &END MGRID
>     &QS
>       EPS_DEFAULT 1.0E-8
>     &DISTRIBUTION
>       SKIP_OPTIMIZATION TRUE
>     &END DISTRIBUTION
>     &END QS
>     &SCF
>       EPS_SCF 1.0E-7
>       SCF_GUESS ATOMIC
>       MAX_SCF 500
>       ADDED_MOS 50
>       &DIAGONALIZATION T
>       &END DIAGONALIZATION
>       &OUTER_SCF
>          OPTIMIZER DIIS
>          MAX_SCF 30
>        &END OUTER_SCF
>        &SMEAR
>          METHOD FERMI_DIRAC
>          WINDOW_SIZE 0.007349862
>        &END SMEAR
>     &END SCF
>     &XC
>      DENSITY_CUTOFF 1.0e-9
>      &XC_GRID
>       XC_SMOOTH_RHO SPLINE3
>       XC_DERIV SPLINE3_SMOOTH
>      &END XC_GRID
>      &XC_FUNCTIONAL
>       &PBE
>       &END PBE
>       &END XC_FUNCTIONAL
>     &END XC
>   &END DFT
>   &SUBSYS
>     &CELL
>       ABC 7.3 7.3 18.65
>     &END CELL
>     &COORD
>  Cu         0.0000000000        0.0000000000        0.0000000000
>  Cu         1.8250000000        1.8250000000        0.0000000000
>  Cu         0.0000000000        3.6500000000        0.0000000000
>  Cu         1.8250000000       -1.8250000000        0.0000000000
>  Cu         3.6500000000        0.0000000000        0.0000000000
>  Cu        -1.8250000000        1.8250000000        0.0000000000
>  Cu         3.6500000000        3.6500000000        0.0000000000
>  Cu        -1.8250000000       -1.8250000000        0.0000000000
>  Cu        -1.8250000000        0.0000000000        1.8250000000
>  Cu         3.6500000000        1.8250000000        1.8250000000
>  Cu        -1.8250000000        3.6500000000        1.8250000000
>  Cu         3.6500000000       -1.8250000000        1.8250000000
>  Cu         1.8250000000        0.0000000000        1.8250000000
>  Cu         0.0000000000        1.8250000000        1.8250000000
>  Cu         1.8250000000        3.6500000000        1.8250000000
>  Cu         0.0000000000       -1.8250000000        1.8250000000
>  Cu         0.0027629890        0.1810678691        3.5521582796
>  Cu         2.0009703441        1.8306590329        3.7419132473
>  Cu         0.0012714586        3.5522008702        3.5509776811
>  Cu         1.6331335266       -1.8263840871        3.6506701186
>  Cu        -3.6527301762       -0.2667803211        3.6469179283
>  Cu        -1.9117113169        1.8216433088        3.8247004427
>  Cu        -3.6354479501       4.00316486646        3.6502743039
>  Cu        -1.5520623914       -1.7336304355        3.6519202615
>   C        -3.6540423726        1.2728466111        5.0359160553
>   C        -3.6577740344        2.5275816699        5.0430626704
>   H        -3.6575062980        0.6958416548        5.9483529244
>   H        -3.6560211188        3.0906730999        5.9596030311
>     &END COORD
>     &KIND Cu
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       POTENTIAL GTH-PBE-q11
>     &END KIND
>     &KIND C
>       BASIS_SET TZV2P-MOLOPT-GTH
>       POTENTIAL GTH-PBE-q4
>     &END KIND
>     &KIND H
>       BASIS_SET TZV2P-MOLOPT-GTH
>       POTENTIAL GTH-PBE-q1
>     &END KIND
>   &END SUBSYS
> &END FORCE_EVAL
> &GLOBAL
>   PROJECT cuc2h2_pbe
>   PREFERRED_FFT_LIBRARY FFTSG
>   RUN_TYPE GEO_OPT
>   PRINT_LEVEL LOW
> &END GLOBAL
> &MOTION
>   &CONSTRAINT
>     &FIXED_ATOMS
>        LIST 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
>     &END FIXED_ATOMS
>   &END CONSTRAINT
>   &GEO_OPT
>     MAX_ITER 300
>     MAX_FORCE 1.E-7
>     OPTIMIZER BFGS
>   &END GEO_OPT
> &END MOTION
>
> Any help/tips/comments/suggestions would be greatly appreciated.