[Pw_forum] dynamical matrices

[Paolo Giannozzi]

On Thursday 14 April 2005 11:54, Jonathan Breeze wrote:

> Is there a reason why the dynamical matrices produced by ph.x
> are not divided by the square root of the masses of both atoms?

because they can be easily divided at a later stage, and you might
want to change the masses, for instance in the "mass approximation"
or to calculate the isotopic effect. Both ph.x and auxiliary programs in
pwtools/ divide the dynamical matrix by the square root of the masses
before diagonalization. The resulting eigenvectors are normalized; the
corresponding atomic displacements are the eigenvectors divided by
the square root of the masses

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
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