FAQ¶
Which DFTB parameters are available?¶
The DFTB module in the Amsterdam Modeling Suite ships with the following parameters:
GFN1-xTB: extended Tight Binding parameters for elements H-Rn (all spd elements). Can be used for all properties.
Quasinano 2013: electronic parameters for H-Po, La, Th. Enabling electronic properties like band structures, DOS, UV/VIS, NEGF
Quasinano 2015: + repulsive parameters for H-Ca, Br. Enabling geometry optimization, IR spectra, MD.
Dresden parameters: C, H, O, N, P, S, Al, Si, Ti, Cu, Na, see $ADFHOME/atomicdata/DFTB/Dresden/README
DFTB.org parameters (see Readme or dftb.org website for latest info). Encrypted parameters may also be evaluated during trial
Dispersion corrections available (Grimme’s D2 & D3(BJ), London, UFF)
Can I use Grimme’s D3(BJ) dispersion corrections?¶
Yes, with DFTB3 and either the Quasinano or the DFTB.org 3ob parameters sets. With other DFTB methods and parameter sets you can use D2, London (ULG) or UFF dispersion.
Do you have the extended Tight-Binding (xTB) parameters?¶
We have implemented Grimme’s first GFN-xTB method (GFN1-xTB). The second set (GFN2-xTB) usually does not improve accuracy much and has not yet been implemented.
Can I include electric fields?¶
Yes.
Can I study 1D periodic systems like carbon nanotubes?¶
Yes, DFTB can be applied to 0D systems (molecules), 1D systems (polymers, nanotubes), 2D systems (surfaces), and 3D systems (bulk).
For 1D and 2D systems we have proper periodic boundary conditions. So you do not need to work with large unit cells and slab-gap approximations.
All DFTB parameters can be used for all periodicity.