[Pw_forum] dos

[Axel Kohlmeyer]

On Fri, 2009-05-08 at 14:28 +0200, Lorenzo Paulatto wrote:

> > How can I project dos to molecular orbital?
> 
> You cannot, there are no molecular orbitals defined in Quantum-Espresso.  
> Implementing it is probably far from trivial, as molecular orbitals are  
> not easy to define in the plane-wave formalism.

one comment. 

in a strict sense, there are no molecular orbitals
in a periodic calculation. they become bands.

however, people have tried to find an approximation that would
work reasonably well for molecular crystals (you'd assume that
the molecules don't interact, which they do). for this you
first run a localization procedure and compute the wannier centers
and orbitals, then you determine which atoms belong to a molecule
and then distribute the wannier centers and orbitals to those 
molecules and diagonalize the resulting submatrices again.

now in principle you could use those orbitals to project onto
for a pDOS calculation. 

needless to say, that this all would require some programming
to implement it in Q-E.

cheers,
    axel.

-- 
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Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
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