[Pw_forum] Can I obtain IR spectrum from CPMD trajectory in Quantum Espresso?

[Nicola Marzari]

On 29/07/2015 18:08, Pascal Boulet wrote:
> Hello,
>
> Isn’t it possible to get IR spectra from the FFTs of the atomic velocity
> autocorrelation function?
>
> Pascal
>


Hi Pascal,

that would give you the vibrational density of states - to get an IR
spectrum you need to understand how the system couples with an electric
field, hence the need to calculate the dipole of a finite system
or the polarization of an extended one.

				nicola

-- 
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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project