Additional Input Options

System Properties

DFTB can calculate various properties of the simulated system.

Properties
  {BondOrders {true|false}}
  {NBOInput {true|false}}
  {DipoleMoment {true|false}}
End

Specifying neither true nor false is the same as specifying true.

BondOrders

(Default: false) Whether or not Mayer bond orders are calculated based on the final molecular orbitals. The calculated bond orders will be picked up by the GUI and shown in ADFMovie for geometry optimzations and molecular dynamics calculations.

NBOInput

(Default: false) Whether or not an input file for the NBO program is written to disk as nboInput.FILE74. The input file follows the FILE47 format as described in the NBO6 manual available on nbo6.chem.wisc.edu. By default, only the calculation of the natural bond orbitals and the natural localized molecular orbitals is enabled, but the nboInput.FILE47 file can be edited by hand to enable other analysis models. Please refer to the NBO6 manual for details.

DipoleMoment

(Default: true) Whether of not the electric dipole moment is calculated from the calculated Mulliken charges. While it is technically possible to calculate the dipole moment with the DFTB0 model, it is not recommended and the SCC-DFTB or DFTB3 model should be used instead. For periodic systems the dipole moment is ill-defined and should not be interpreted.

Restart

Allows to restart DFTB-SCC (and DFTB3) calculations from atomic or shell charges (or spin populations) generated in earlier runs.

Restart
      {RestartFile RestartFileName}
      {RestartMulliken true|false}
      {RestartSpinPops true|false}
      {RestartGeometry true|false}
End

For spin-restricted calculations restarting requires requires a valid .rkf file to be present at the (absolute or relative) path specified by RestartFileName and the key RestartMulliken to be enabled. In the context of spin-resolved DFTB runs a restart can either performed via RestartMulliken and/or RestartSpinPops. In the latter case the restart .rkf file is required to contain spin populations computed in a previous spin-resolved calculation.

The RestartGeometry key can be used to read the last nuclear coordinates (and potentially the lattice) from the restart file. This can be used to restart a failed or non-converged geometry optimization from the last known coordinates. Note that the entire System block must still be present, even when restarting with the geometry from another file. The coordinates given in the Atoms block (and potentially the lattice) will be ignored, but the number the type and the order of the atoms is used and must match with the system in the restart file.

Developer options

Print
  timers {None | Normal | Detail | TooMuchDetail}
End

Printing timing details to see how much time is spend in which part of the code. Default value is None.