[Pw_forum] a question for projwfc.x

[Axel Kohlmeyer]

On Mon, 19 Jan 2009, vega lew wrote:

VL> Dear all,
VL> 
VL> in input file description of projwfc.x, it's said that the code could
VL> identify the different contribution of Px, Py and Pz, or D sub orbitals.
VL> 
VL> I wonder if there is a literature describe the algorithm and the  physical
VL> meaning in detail.

have a look into a text book on linear algebra and look up projections.

pw.x uses a plane wave basis set, projwfc.x projects the wavefunction
expressed in the plane wave basis upon the atomic pseudowavefunctions
stored in the pseudopotentials (which is not perfect, btw. some part
of the wavefunction will remain unassigned, since you are using an
incomplete basis). the physical meaning is that one tries to attribute
the contributions from the individual atoms to the individual states.

the process is similar to, say, expanding an irrational function
through a polynomial and then try to describe the original function
through the contributions of the individual "power of x" coefficients.

cheers,
  axel.

VL> 
VL> thank you for reading
VL> 
VL> vega
VL> 

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