[Pw_forum] PBE0 convergence

[Jie Jiang]

Dear Gabriele Sclauzero,

Thanks,

Jie

On Wed, Jun 1, 2011 at 3:05 AM, Gabriele Sclauzero <sclauzer at sissa.it>wrote:

> Dear Jie Jiang,
>
>     Are you sure that your atomic structure is correct? We cannot judge
> since you did not provide the atomic positions. You can check by yourself
> using xcrysden, for instance. Do the standard PBE calculations work well and
> give meaningful results? For PBE0, you can maybe try to reduce the
> mixing_beta, or use another mixing scheme. Finally, are you sure about your
> k-point sampling? Your cell has celldm(2)=b/a < 1, then b<a, so why do you
> use more k-points along the first direction? I would rather use 3 6 1,
> instead of 6 3 1.
>
> Regards,
>
>
> in the behalf of Mr. PWscf,
>
>    GS
>
>
> Il giorno 31/mag/2011, alle ore 15.10, Jie Jiang ha scritto:
>
> Dear PWscf,
>
> I get a problem in PBE0 convergence. Below is part of the input file,
>
> &CONTROL
>   calculation  = "scf",
> /
> &SYSTEM
>   ibrav     = 12,
>   celldm(1) = 15.73981,
>   celldm(2) = 0.62519,
>   celldm(3) = 4.39673,
>   celldm(4) = 0.62519,
>   nat       = 58,
>   ntyp      = 5,
>   ecutwfc   = 80.0,
>   input_dft = 'pbe0',
>   nqx1 = 2, nqx2 = 1, nqx3 = 1,
>   exxdiv_treatment= 'gygi-baldereschi'
>   ecutvcut = 0.7
>   x_gamma_extrapolation= .TRUE.
>   occupations = "smearing",
>   smearing    = "methfessel-paxton",
>   degauss     = 0.01,
> /
> &ELECTRONS
>   conv_thr    = 1.D-6,
>   mixing_beta = 0.5D0,
> /
> ATOMIC_SPECIES
> C     12.0107
> S     32.066
> H     1.00794
> O    15.9994
> Zn   65.409
> /
> K_POINTS {automatic}
>  6 3 1 0 0 0
>
> The output 'dexx' is
>
>      est. exchange err (dexx)  =       0.00059720 Ry
>      est. exchange err (dexx)  =      -0.02431459 Ry
>      est. exchange err (dexx)  =      -0.02596414 Ry
>      est. exchange err (dexx)  =      -0.02720608 Ry
>      est. exchange err (dexx)  =      -0.02821286 Ry
>      est. exchange err (dexx)  =      -0.02946368 Ry
>      est. exchange err (dexx)  =      -0.03148666 Ry
>      est. exchange err (dexx)  =      -0.03481403 Ry
>      est. exchange err (dexx)  =      -0.03964928 Ry
>      est. exchange err (dexx)  =      -0.04531623 Ry
>
> and Fock energy is
>
> -177.9185854736362
> -177.9185854736362        -177.8610717829301        -177.8047524875259
> -177.8047524875259        -177.8356769333793        -177.8179722072562
> -177.8179722072562        -177.8457748551563        -177.8216492155755
> -177.8216492155755        -177.8490273372818        -177.8219932983469
> -177.8219932983469        -177.8500300290520        -177.8216410368603
> -177.8216410368603        -177.8505498629616        -177.8205313239625
> -177.8205313239625        -177.8511288881755        -177.8187531280260
> -177.8187531280260        -177.8519180436694        -177.8154548907789
> -177.8154548907789        -177.8530355735678        -177.8113176980133
> -177.8113176980133        -177.8542927054368        -177.8066352532881
>
> Can you please help me in this issue.
>
> Thanks,
>
> Jie Jiang
>
> Applied Physics
> Yale University
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>
>
> § Gabriele Sclauzero, EPFL SB ITP CSEA
> *   PH H2 462, Station 3, CH-1015 Lausanne*
>
>
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