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["Wu Rongqin" <g0203654@nus.edu.sg>]

Dear Dr Ghosez,

    I find that the dielectric tensor from abinis run is actually the 
dielectric tensor for zero frequency. However, in your publications you gave 
lot of tensor at infinite frequency. How to do such a calculation? Give me 
some hints, please

    Rongqin Wu

-----Original Message-----
From: Philippe Ghosez [mailto:Philippe.Ghosez@ulg.ac.be] 
Sent: 2004年1月7日 15:39
To: forum@abinit.org
Subject: Re: [abinit-forum] Soft Phonon modes

>Hello all abinit users and good year:
>I want to know more on soft modes of vibrations (courses, 
>publications..), can't anyone  help me and send some references 
>related to this subjects
>
>thank you very much.

Hello,

Some informations on the origin of unstable modes and structural 
instabilities in ferroelectric compounds are available in lecture 
notes accessible at the following address:

http://www.ulg.ac.be/phythema/Head/publi.htm

Look for the course :
"Microscopic Properties of Ferroelectric Oxides
from First Principles: Selected Topics"
( file :  Lecture_Ferro-1-May02.ps.gz )

There are some informations in the Chapter on
the lattice dynamics.

Best wishes,

Philippe GHOSEZ.


----------------------------------
Philippe GHOSEZ
Universite de Liege
Institut de Physique, Bat. B5
Allee du 6 aout, 17
B- 4000 Sart Tilman
BELGIUM

Phone : ++(32) (0)4-366.36.11
Fax   : ++(32) (0)4-366.29.90
E-mail: Philippe.Ghosez@ulg.ac.be

http://www.ulg.ac.be/phythema
----------------------------------