[Pw_forum] cu/semiconducting system

[Duy Le]

what's wrong? why don't you use non-zero gaussian spreading?
The purpose of using smearing is to avoid a step function at Fermi
level. If the system is metallic, gaussian spreading must be non-zero.
If it is not metallic, a non-zero gaussion spreading won't harm your
calculation.
--------------------------------------------------
Duy Le
PhD Student
Department of Physics
University of Central Florida.

"Men don't need hand to do things"



On Fri, Aug 27, 2010 at 3:29 PM, chengyu yang <chengyu.young at gmail.com> wrote:
> Dear all,
>           If I have a copper/carbon nanotube system, and the nanotube is
> semiconducting, what value should the degauss be ?Is it still a metallic
> system? I used the degauss as 0,but it was wrong. I'm a little confused.
>  thank you.
>
> &CONTROL
>                  calculation = 'scf' ,
>                 restart_mode = 'from_scratch' ,
>                        prefix = '22' ,
>  /
>  &SYSTEM
>                        ibrav = 6,celldm(1) = 21.764541128,celldm(3)=0.
> 213765379
>                          nat = 10,ntyp = 2,ecutwfc = 75 ,
>                      occupations='smearing', smearing='gaussian', degauss=0
>  /
> &ELECTRONS
>                     conv_thr = 1.0d-8 ,
>                  mixing_beta = 0.7 ,
>  /
> ATOMIC_SPECIES
>     C   12.01100  C.pz-vbc.UPF
>     Cu  63.55     Cu.pz-d-rrkjus.UPF
>
> ATOMIC_POSITIONS angstrom
>   C        1.402181    -0.000000    -1.233916
>   C        0.682146     1.225067    -1.233916
>   C       -0.000000     1.402181    -0.000000
>   C       -1.225067     0.682146    -0.000000
>   C       -1.402181    -0.000000    -1.233916
>   C       -0.682146    -1.225067    -1.233916
>   C       -0.000000    -1.402181    -0.000000
>   C        1.225067    -0.682146    -0.000000
>   Cu       0            2.804362      0
>   Cu      -1.402181     2.428648737   0
>
>
> K_POINTS automatic
>     1 1 5 0 0 0
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