[Pw_forum] Single Chain of molecule

[Axel Kohlmeyer]

On Sun, 25 Dec 2005, Diep Vinh Quang wrote:

VQ> Dear Pwscf users,

dear vinh,

VQ> Could you please tell me what is the value of "ibrav" for one dimensional system?

there is none. with a code like pwscf, you always have a system 
that is periodic in three dimension.

VQ> For example, I would like to calculate the band structure of a chain of Polyethylene
VQ> C2H4. I can constructe the position of the atoms but I don't know how to declare the
VQ> bravais lattice.

your best shot is probably using a large enough orthorhombic supercell, 
e.g.

  ibrav=8, a=2.5182343800, b=10.0, c=10.0

you have to make sure that b and c are large enough, so that 
the periodic images do not influence each other. since your 
system is pretty non-polar this should work well. 

regards,
    axel.

VQ> 
VQ> Any helps are appricated.
VQ> 
VQ> Bests
VQ> 
VQ> Vinh
VQ> Ps. Ex          ATOMIC_POSITIONS {angstrom}
VQ>                C -0.6295585950 -0.4167504952 0
VQ>                 H 0.0115649288 -1.048383796 0
VQ>                 H -1.270682119 -1.048383796 0
VQ>                 C 0.6295585950 0.4167504952 0
VQ>                 H -0.0115649288 1.048383796 0
VQ>                  H 1.270682119 1.048383796 0
VQ> 
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VQ> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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If you make something idiot-proof, the universe creates a better idiot.