The ABINIT Users Mailing List ( CLOSED )

["Patrick B. Hillyard" <phillyar@stanford.edu>]

Dear ABINIT users,
I am attempting to investigate phonon density of states projected onto a 
certain direction.  I would like to weight the phonon DOS by the dot 
product of the phonon polarization vector and the lattice vector of 
interest.  I have modified the relevant portions of the ANADDB code to 
output the necessary information for each q point (frequency, qpt, 
weight of qpt, eigen/displacement vector).

I am dealing with a multiple atom per unit cell system.  My questions 
are with respect to obtaining the polarization vector.  It seems to me 
that the polarization vector should be proportional to the displacement 
vector.  Is this correct?  I ask this because I believe the polarization 
vector should be the same for each atom for a given mode/q point. 
However, when I output the displacements, I observe atoms displacing in 
different directions...  Am I making wrong assumption regarding the 
polarization vector and its relationship to the displacement vector?

Also, I observe imaginary displacement components for nonzero q.  What 
is the physical meaning of an imaginary displacement component.  Is the 
physically observable displacement the complex magnitude or is it just 
the real component of the displacement vector?

If you have made it this far, thanks for reading...  And thanks for any 
help!!!

-Patrick Hillyard