[Pw_forum] About: the system is metallic, specify occupations?

[degironc]

A system with an even number of electron per unit cell is an isulator or 
a metal
according to whether or not these electrons (doubly) occupy completely a 
set of  bands
separated from the subsequent ones by an energy gap.
A system with an odd number of particles can't possibly do that (if it 
is not magnetic).
In PWscf when dealing with a metal or a magnetic system you need to 
specify how
to describe partial occupation of energy bands.
Relevant input variables are: occupation, smearing, degauss in the 
system namelist
best,
   stefano

PS: please note that in crystal coordinates

    H      0.000000000    0.000000000    3.250000000

is equivalent to

    H      0.000000000    0.000000000    0.250000000

is this what you want ???



Rahmat Gunawan wrote:

>Dear PW_Forum...
>
>I have tried some examples to know how graphite system can learned in
>PWscf. I read some article in journals: J.Phys.Chem. B., 2006, 110, 14832
>and J.Chem.Phys., 118(3), 1003. I have problem about input, now I consult
>to PW_Forum my interaction bond input of "graphite---H"
>
>&CONTROL
>                 calculation = 'scf' ,
>                restart_mode = 'from_scratch' ,
>                      outdir = '/home/s3/s305igun/tmp/' ,
>                  pseudo_dir = '/home/s3/s305igun/pseudo/' ,
>                      prefix = 'C' ,
>                     tstress = .true. ,
>                     tprnfor = .true. ,
> /
> &SYSTEM
>                       ibrav = 4,
>                   celldm(1) = 4.64117,
>                   celldm(3) = 2.7264,
>                         nat = 5,
>                        ntyp = 2,
>                     ecutwfc = 25.0 ,
>                     ecutrho = 100.0 ,
> /
> &ELECTRONS
> /
>ATOMIC_SPECIES
>    H    1.00794  H.vbc.UPF
>    C   12.01100  C.pz-vbc.UPF
>ATOMIC_POSITIONS crystal
>    H      0.000000000    0.000000000    3.250000000
>    C      0.000000000    0.000000000    0.000000000
>    C      0.333333333    0.666666666    0.000000000
>    C      0.000000000    0.000000000    0.500000000
>K_POINTS
>  10
>   0.1250000  0.1250000  0.1250000   1.00
>   0.1250000  0.1250000  0.3750000   3.00
>   0.1250000  0.1250000  0.6250000   3.00
>   0.1250000  0.1250000  0.8750000   3.00
>   0.1250000  0.3750000  0.3750000   3.00
>   0.1250000  0.3750000  0.6250000   6.00
>   0.1250000  0.3750000  0.8750000   6.00
>   0.1250000  0.6250000  0.6250000   3.00
>   0.3750000  0.3750000  0.3750000   1.00
>   0.3750000  0.3750000  0.6250000   3.00
>
>I need your help, is it true input? because at output file write: "the
>system is metallic, specify occupations?" I do not understand about this
>statements.
>
>Thanks very much, succes for your research
>
>Sincerely yours.
>
>Rahmat gunawan
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>  
>