[Wien] Constructing a Supercell

[Mat Ogawa]

Dear all:

I'd like to do similar calculation of electronic structure of
Si QWR described in PRB 77, 075431(2008).

I made a super cell of 1x1x1 with 5 bohr vacuum layers in x and y
direction by the aid of "supercell," which is hopefully a model
for the smallest QWR.  I ran "StructGen," and it suggested
other symmetry (3_P2, see attachment) than the previous one (Primitive
lattice Nonequiv. Atoms 8).
I checked the generated structure by XCrysDen. Then I followed the
suggestion
but, as suspected, there were many lines in the band structures probably
due to dangling bonds.

I'd like to ask two questions:

1) Is the suggested symmetry always acceptable for the following
   calculations ()?
2) Could anyone teach me how to terminate the dangling bonds
   of the surface atoms by other atoms (e.g. hydrogen)?

  (I suppose I have to check which Si locates at the surface, then
   add hydrogen atom to it by giving appropriate position.
   My concern is that the positions of hydrogen may impair the
   symmetry and result in wrong results or take a long time for
   SCF calculation.)

Although I searched if there are similar questions in the previous
mails
http://zeus.theochem.tuwien.ac.at/pipermail/wien/
or in the faq
http://www.wien2k.at/reg_user/faq/supercells.html,
I failed to find any. So I'd appreciate any reply.

Kind regards,
Matthew
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