The ABINIT Users Mailing List ( CLOSED )

[Marek Veithen <Marek.Veithen@ulg.ac.be>]

Dear Chris,

for the moment, ABINIT is able to compute third-order derivatives of the
energy with respect to 3 electric fields (related to the non-linear optical
susceptibilities) and with respect to 2 electric fields and 1 atomic 
displacement
(related to the Raman tensors).

The third-order energy derivatives with respect to 3 atomic displacements
(related to the anharmonic force constants) are not available yet
in spite of the fact that you can specify these quantities in your input 
file
using rf[1-3]phon, rf[1-3]atpol and rf[1-3]dir.

Best regards,
Marek

brown05@auburn.edu wrote:

> Is ABINIT able to do third order derivative calculations for phonons by using the  input variables rf1phon, rf1atpol, and rf1dir?  When I try to test the calculation on Si in the diamond structure at the gamma point for both the phonon datasets, the code finishes, but the third-derivative matrix it outputs is empty.  Am I missing something obvious? 
>
> Thanks,
> Chris Brown 
>
>
>  


--
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