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["M.G.A.Tijssens" <M.G.A.Tijssens@LR.TUDelft.NL>]

Hello everybody,

I am trying to calculate eigenfrequencies and -modes from the
dynamical matrices I obtained from abinit. However I cannot make
the numbers match. Simply using D.u = \omega^2 u for the eigenvalues
and then freq=\omega/(2\pi) gives results inconsistent with the solution
obtained with ifc.

So, can anyone explain to me (or point me to a source of information)
how the eigenfrequencies and -modes in ifc are determined
from the dynamical matrix obtained from a RF-calculation with abinit?

And can anyone tell me how one gets from eigenvalues from the dynamical
matrix to eigenfrequencies in Thz and cm^{-1} (what 'factors' are used
to transform the units)?

Thanks,
Martin Tijssens
-- 
Dr. M.G.A. Tijssens               T: +31 15 278 9552
Delft University of Technology    F: +31 15 261 1465
Dept. of Aerospace Engineering    E: M.G.A.Tijssens@lr.tudelft.nl
Postbus 5058                      O: 1.54
2600 GB  Delft                    U:
http://www.em.lr.tudelft.nl/~tijssens
The Netherlands