[Pw_forum] OPTIONAL VARIABLES FOR RAMAN

[Paolo Giannozzi]

On Nov 12, 2010, at 14:09 , Eduardo Ariel Menendez Proupin wrote:

> Hi, Where can I read the meaning of these options of the PHONON code ?

you can read the meaning of those options...in your message! Seriously:
what you reported is more or less all the available documentation of  
those
variables, which you shouldn't need to set in normal circumstances. In
order to know more, you have to know the details of the algorithm

>       Variable:       eth_rps
>       Description:    Threshold for calculation of  Pc R |psi>.

more exactly, threshold used in the solution of the linear system
(H-\epsilon_v) x |\psi_v> = [H,x]|\psi_v>

>       Variable:       eth_ns
>       Description:    Threshold for non-scf wavefunction calculation.

Needed to calculate |\psi_{k+\delta q}>

>       Variable:       dek
>       Description:    Delta_xk used for wavefunction derivation wrt k.

this is actually \delta q above, because du_q/dq, with u_q=periodic part
of the wavefunction, is used in the calculation of second-order response

No warranty - P.
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Paolo Giannozzi, Dept of Chemistry&Physics, Univ. Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222