[Pw_forum] Debye temp, phonon DOS and sum rules.

[Paolo Giannozzi]

On Jan 24, 2007, at 9:50 , Miguel Martínez Canales wrote:

> 1) Is trying to calculate the Debye temperature from the phonon DOS
> too naïve?

It should be possible; for sufficiently isotropic dispersions you might
also try to estimate the coefficient c in w(q)=cq for q->0

> 2) What are the practical differences between simple and crystal asr?

'simple' asr consists in modifying the diagonal term only of the force
constant matrix so that the sum over all atoms of the induced forces
is zero. 'crystal' asr modifies the matrix in such a way to conserve the
symmetry, I think.

> Could be translated to: What does "optimized corrections of the IFC"
> in pwtools/q2r.f90 mean?

it means that you have to read the original reference, if any (try this:
PRB 71, 205214 (2005) )

> 3) Is the hoop I'm seeing at around 17cm-1 a van Hove singularity I  
> haven't
> covered in my dispersion curves or something more profound?

hard to say, especially without seeing

Paolo
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Paolo Giannozzi, Democritos and University of Udine, Italy