The ABINIT Users Mailing List ( CLOSED )

[xhongjun <xhongjun@mail.ustc.edu.cn>]

Marek Veithen wrote:
> Dear Xianghjun,
>
> I am implementing the computation of Raman activities of zone-center
> optical phonons as well as the non-linear optical tensor d_ijk
> into the ABINIT code.
>
> These features work properly within ABINITv4.0.3
> at least for uniaxial crystals and pseudopotentials without non-linear 
> core correction.
> You should have a look at the test t83 in the Test_v3 directory to
> get an idea of how the computaion of third-order energies works.
> It might also be interesting for you
> to read the slides of my communication at the ABINIT workshop
> that are available at the community webpage
>
>  http://cst-www.nrl.navy.mil/~erwin/abinit/workshop02/presentations/
>
> If you are intended to use the non-linear repsonse part of ABINIT
> in a systematic way, than I suggest
> you not to use ABINITv4.0.3 as it is available on the web page but I
> will send you a beta version of the code I am working on at the moment.
>
> In fact, the computation of third-order energies is not very optimized 
> within
> ABINITv4.0.3. For example, the non-linear response part does not take
> into account the symmetry operations to reduce the number of perturbations
> that have to be computed explicitely. This makes the calculations
> quite cumbersome. Moreover, at the stage of ABINITv4.0.3, the code only 
> computes
> the "bare" third-order energies and you have to perform all 
> transformations by hand
> to get the relevant physical quantities.
>
> The version I am working on at the moment presents some additional features
> that make the computation of third order energies more efficient and
> allow an easier analysis of the results. In particular it presents
> the following caracteristics
>
>     * Use of symmetry operations;
>     * Direct output of d_ijk + first-order changes of the dielectric 
> tensor due to individual
>        atomic displacements;
>     * Output of third-order energies into a DDB that can be merged with 
> a DDB of
>         the linear response part and analysed with ANALDDB (IFC).
>
> These features will probably be available within ABINITv4.1 but
> I can send you a beta version if you are interested.
>
> Best regards,
>
> Marek
>  
>
> --
> Marek VEITHEN
> Universite de Liege
> Institut de Physique, Bat. B5
> Allee du 6 aout, 17
> B- 4000 Sart Tilman
> BELGIUM
>
> Phone : ++(32) (0)4-366.36.12
> Fax   : ++(32) (0)4-366.29.90
> E-mail: Marek.Veithen@ulg.ac.be
>
>  

Dear Marek:
  Thanks for your reply.I am very interested in the  beta version of 
the code you have developed.Please send me a copy.

Best regards,
xianghjun