[Pw_forum] complex band of Cu(111)

[Letizia Chiodo]

Dear Manoj

at a first sight, I can see some errors in your input:
- if you want to model a surface, in the supercell approach, you need
to create a slab + vacuum geometry, I'm not sure you are doing this.
- in general, 3 layers is a very bad choice for describing
(semiconductor or metal) surfaces, you will be very far from
convergence for structural, electronic, etc properties.
- ecutwfc sounds to me too low for Cu, and for ultrasoft
pseudopotentials, you are missing the cutoff on rho.
- and probably I'm forgetting other things, e.g. mixing_beta=0.7 maybe
is too large.

Hope it helps
Letizia

NNL of CNR-INFM, Lecce, Italy,
UPV-EHU, San Sebastian, Spain

On Mon, Jun 23, 2008 at 10:19 PM, Manoj Srivastava <manoj at phys.ufl.edu> wrote:
> Dear PWSCF users,
>  I am a new user of PWSCF and I have encountered a problem in calculating
> complex band of Cu(111). I see a band gap and there are no bands crossing
> Fermi energy. which is obviously wrong :(
> I have used hexagonal unit cells containing 3 atoms. Cu.pz-d-rrkjus.UPF
> pseudo potential was used in the calculation. It would be great if
> somebody can suggest me something.
> Following is the input file I used -
>
>  &system
>    ibrav =4,
>    celldm(1) =4.78076379, celldm(3)=2.44948974,
>    nat= 3,
>    ntyp= 1,
>    nelec=33.0,
>    nbnd=24,
>    ecutwfc =25.0,
>    occupations= 'smearing',
>    smearing='gaussian',
>    degauss=0.02
>
>  /
>  &electrons
>    diagonalization='$diago'
>    conv_thr = 1.0e-8
>    mixing_beta=0.7
>  /
>  ATOMIC_SPECIES
>  Cu       63.55  Cu.pz-d-rrkjus.UPF
>  ATOMIC_POSITIONS {bohr}
>  Cu  0.0          0.0          0.0
>  Cu  2.390381895  1.380087631  3.903477289
>  Cu  4.780763790  2.760175261  7.806954578
> K_POINTS (automatic)
> 8 8 8  0 0 0
> EOF
> # complex bands of cu(111) along the 001 direction K_perp=0
> cat > cu.cond.in << EOF
>  &inputcond
>    outdir='$TMP_DIR/'
>    prefixl='cu'
>    band_file ='bands.cu'
>    ikind=0
>    energy0=10.d0
>    denergy=-0.2d0
>    ewind=3.d0
>    epsproj=1.d-7
>  /
>    1
>   -1.0 1.732 -0.8165
>    100
> EOF
>
>
> Regards,
> Manoj
>
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