[DFTB-Plus-User] Vibrational spectra saga continued

[Andrei Buin]

Thanks B?lint, it helped.  Now, i have the following problem. I'm trying
to get vibrational spectra by fourier transforming  velocity-velocity
auto-correlation function, and i get noise. It is interesting, if i
increase the unit cell size i get different noise pattern. I was
wondering does DFTB+ does only Gamma point MD or K-sampling is
included ? If i do the same with dl_poly it gives reasonable phonon DOS.
Sampling time is at least 10 ps. I'm doing bulk TiO2 system, with 6
atoms in the unit cell with 8x8x8 sampling and 72 atoms with 2x2x2
sampling. I don't think there should be problem with SK parametrisation
since these parameters has been tested at least for the bulk.

Any ideas ?

Thanks. 

With Best Regards, Andrei Buin.