[DFTB-Plus-User] mode problem

[Bálint Aradi]

Dear Zha,

>       I am trying to calculate phonon mode of my system.  I could't find
> the MODE  program on the www.dftb-plus.info website although the mode
> mannual and input file example was found. To my knowledge, the density
> functional pertubation theory (DFPT) and frozen phonon approach were
> generally applied in most computational software. what's the principle
> of the MODE program in DFTB+? Could you tell me where to obtain the MODE
> program and its principle? Thank you very much!


 The mode program you can download from the same place, where you can
download DFTB+ (restricted area, you need to enter you user name and
password). Currently, the vibrations are calculated rather crude: The
Hessian is calculated via finite displacements, then with mode, you can
diagonalize it. You would obtain the phonon spectrum in the Gamma point
only. (Or if you enlarge your real space supercell, in all the points
which folds into the Gamma point.)

 Best regards,

  Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/en/~b_aradi


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