[Pw_forum] Band structure calculation HOWTO

[Janos Kiss]

Dear PWSCF mailing list members,

I am a novice user of this code, and i intend to do some band structure 
calculations on a metallic O-terminated polar wurtzite ZnO surface, 
represented with a periodically repeated H-doped hexagonal slab. 
I have found a nice tutorial on the band structure calculation of bulk Si: 
http://people.sissa.it/~degironc/QE-Tutorial/tutorial_pwscf_ex.pdf
http://people.sissa.it/~degironc/QE-Tutorial/examples_pwscf_ex.tgz

Although i have followed the instructions in the tutorial very carefully, 
once i try to plot the band structure with the plotband.x it is clear that the 
minimum/maximum energy values and the Fermi energy is different (with more 
than an eV) compared with the values presented in this tutorial. Beside this 
problem the band structure also shows a feature in the Sigma to 
Gamma point path not present in the tutorial's plot.
I'm just wonderind where this discrepancy is coming from. Did i 
miscompile the code, or eventually the tutorial was done by mistake with 
different settings/pseudopotential? 

Because i have a metallic system, besides the cutoff i should converge with 
respect to degauss/smearing as well. On which quantities should i keep my eye 
on, when i try to converge with the degauss/smearing? Is there eventually a 
preferred smearing scheme which is easier to converge/handle?
Is there a sample k-point path implemented in the code? (i would like to have 
a k-point path along the Gamma to M, M to K, K to Gamma high symmetry points).
In what extent will be affected the band structure by the smearing scheme if 
eventually the system changes from the metallic state to a semiconductor by 
some adsorbates/surface defects?
Also some other usefull hints/tricks/explanations on what to do or not to do
in a band structure calculation with PWSCF would be greatly appreciated. 

I apologize if these questions are obsolete/redundant, but i could not find a 
straightforward way to search trough the whole content of the mailing list.

Best regards,
  Janos.  

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   Janos Kiss   e-mail: janos.kiss at theochem.ruhr-uni-bochum.de       
 Lehrstuhl fuer Theoretische Chemie  Phone: +49 (0)234/32-26485 
 NC 03/297                                  +49 (0)234 32 26754
 Ruhr-Universitaet Bochum            Fax:   +49 (0)234/32-14045
 D-44780 Bochum            http://www.theochem.ruhr-uni-bochum.de
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