Interface electrostatics

Simple interface that calculates electrostatic energy from provided atomic charges. The atomic charges can be prepared by any other interface that can calculate them.

By default, point charge model is used but two diffuse charge models are also available - spherically symmetric Gaussian and Slater densities. The width of the density for each element is determined from the Hubbard U parameter analogously to to the model used in SCC-DFTB. The parameters were taken from 3OB parametrization of SCC-DFTB.[1]

http://www.dftb.org/parameters/download

Methods and capabilities

The interface implements a single unnamed method; 'method' keyword not necessary

Keywords used

Keywords specific for this interface:

electrostatics_model

Other keywords used by this interface:

atomic_charges_read

Examples

The following examples, along with all other files needed to run them, can be found in the directory cuby4/interfaces/electrostatics/examples

#===============================================================================
# Electrostatics interface example 1
#===============================================================================

# Here, we calculate mulliken atomic charges for water dimer using PM6
# in MOPAC, and use the atomic charges to calculate electrostatic interaction
# between the two molecules.

job: multistep
steps: charges, interaction

calculation_charges:
  job: atomic_charges
  interface: mopac
  method: pm6
  charge: 0
  geometry: S66:water_dimer
  # Write charges to a file
  atomic_charges_write_format: mol2
  atomic_charges_write: charges.mol2

calculation_interaction:
  job: interaction
  interface: electrostatics
  geometry: charges.mol2
  # Read charges from a file
  atomic_charges_read: from_geometry