ExternalPotential

	ExternalPotential
EffectivePotential	TransmissionSpectrum

Name

ExternalPotential — Class for calculating the Hartree potential corresponding to a density.

Synopsis

Namespace: NanoLanguage

ExternalPotential(configuration)

Description

A class for calculating the external potential for a configuration.

ExternalPotential Arguments

configuration

The configuration for which the external potential should be calculated.

Type: Either a MoleculeConfiguration, BulkConfiguration, or a DeviceConfiguration.

ExternalPotential Methods

A ExternalPotential object provides the following methods:

derivatives(x, y, z): Calculate the derivative in the point x,y,z.

x

The cartesian x coordinate.

Type: physical quantity with type length.

y

The cartesian y coordinate.

Type: physical quantity with type length.

z

The cartesian z coordinate.

Type: physical quantity with type length.
evaluate(x, y, z): Evaluate in the point x,y,z

x

The cartesian x coordinate.

Type: physical quantity with type length.

y

The cartesian y coordinate.

Type: physical quantity with type length.

z

The cartesian z coordinate.

Type: physical quantity with type length.
gridCoordinate(i, j, k): Return the coordinate for a given grid index.

i

The grid index in the A direction.

Type: integer

j

The grid index in the B direction.

Type: integer

k

The grid index in the C direction.

Type: integer
nlprint(stream): Print a string containing an ASCII table useful for plotting the external potential.

stream

The stream the external potential should be written to.
Type: A stream that supports strings being written to using 'write'.
Default: sys.stdout
scale(scale): Scale the field with a double.

scale

The parameter to scale with.

Type: float
shape(): Query function for getting the shape of the data.
toArray(): Return the values of the grid as a numpy array slicing off any units.
unit(): Get the unit of the data in the grid.
unitCell(): Return the unit cell for the grid.
volumeElement(): Get the volume element of the grid.

Usage Examples

Calculate the external potential and save it to a file

# Set up configuration
molecule_configuration = MoleculeConfiguration(
    elements=[Nitrogen, Hydrogen, Hydrogen, Hydrogen],
    cartesian_coordinates=[[ 6.13508 ,  5.790587,  2.75    ],	
                           [ 6.13508 ,  6.73176 ,  2.336663],	
                           [ 6.95016 ,  5.32    ,  2.336663],
                           [ 5.32    ,  5.32    ,  2.336663]]*Angstrom 
    )

# Add metallic regions (without them the external potential would be constant)
metallic_region_0 = BoxRegion(
    0*Volt,
    xmin = 0*Angstrom, xmax = 12*Angstrom, 
    ymin = 0*Angstrom, ymax = 12*Angstrom, 
    zmin = 0*Angstrom, zmax = 1*Angstrom
)

metallic_region_1 = BoxRegion(
    1*Volt,
    xmin = 0*Angstrom, xmax = 12*Angstrom, 
    ymin = 0*Angstrom, ymax = 12*Angstrom, 
    zmin = 5*Angstrom, zmax = 6*Angstrom
)

metallic_regions = [metallic_region_0, metallic_region_1]
molecule_configuration.setMetallicRegions(metallic_regions)

# Define the calculator
calculator = HuckelCalculator()
molecule_configuration.setCalculator(calculator)

# Calculate and save the effective potential
external_potential = ExternalPotential(molecule_configuration)
nlsave('results.nc', molecule_configuration)
nlsave('results.nc', external_potential)

nh3_external_potential.py

For examples on how to average and handle 3-d grids, see the examples for ElectronDifferenceDensity and ElectrostaticDifferencePotential.

Notes

ExternalPotential, returns the electrostatic potential due to the electrodes and gates in the system.
To export the grid data of an external potential, use the method nlprint.


EffectivePotential		TransmissionSpectrum