[Pw_forum] PWCOND

[Alexander Smogunov]

Dear Manoj.
The pwcond code was written assuming that the unit cell
starts at z=0 and goes in positive z direction, the direction
of transport. Quite probable that when you invert the
cell it does not work properly... 
Alexander


В Втр, 21/04/2009 в 23:44 -0400, Manoj Srivastava пишет:
> Dear PWSCF users, 
>  I have a question regarding real band structure calculated from
> PWCOND. Complex band code requires kx,ky and E as input and gives kz
> as output. I have noticed that the answer for kz depends whether you have
> unit cell vectors as (a1,a2,a3) or (a1,a2,-a3). I did a calculation for
> Cu(001) with 2 atoms tetragonal unit cell, with the following input file - 
> 
> & control
>     calculation='scf'
>     pseudo_dir = '/home/manoj/espresso-4.0.1/pseudo',
>     outdir='./',
>     prefix='cu',
>  /
>  &system
>     ibrav = 0,
>     celldm(1)=4.7588286373854648
>     nat= 2,
>     ntyp= 1,
>     ecutwfc =150.0,
>     occupations='smearing',
>     smearing='gaussian',
>     degauss=0.02,
>     ecutrho=400
>  /
>  &electrons
>     conv_thr = 1.0e-8
>     mixing_beta=0.7
>  /
> ATOMIC_SPECIES
>  Cu 63.55  Cu.pz-d-rrkjus.UPF
> ATOMIC_POSITIONS
>   Cu 0.0 0.0 0.0
>   Cu 0.5 0.5 0.707106781
> K_POINTS (automatic)
> 8 8 8  1 1 1
> CELL_PARAMETERS
> 1.0 0.0 0.0
> 0.0 1.0 0.0
> 0.0 0.0 1.414213562
> 
> &inputcond
>     outdir='./'
>     prefixl='cu'
>     band_file ='bands.cu'
>     ikind=0
>     energy0=2.d0
>     denergy=-0.5
>     ewind=104.d0
>     epsproj=1.d-6
>  /
>     1
>     0.0 0.0 1.0
>     24
> 
> This gives me reasonable answer and it matches up with existing results. 
> Now when I changed a3 to -a3, so that the unit cell now has become 
> (a1,a2,-a3), the answer does not match up with the previous one. 
> Just to give you one concrete example- 
> at Fermi energy for kx,ky (0,0) for unit cell (a1,a2,a3) we get kz=-0.1571
> while for (a1,a2,-a3) we get kz=0.07323. 
> I understand that for two different set of unit cell vectors we should not
> in general expect k_z to match, but this is a very special example, as it
> is just mirror symmetry about xy plane. so shouldn't  kz in one set have
> value -kz in other?
> Thanks for your attention. 
> 
> Regards, 
> Manoj Srivastava
> Department of Physics 
> University of Florida
> Gainesville, FL  
> 
> 
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-- 
Alexander Smogunov 
Email:     smogunov at sissa.it
Home page: http://people.sissa.it/~smogunov