BlochState

	BlochState
Eigenstate	MullikenPopulation

Name

BlochState — Class for calculating a Bloch state

Synopsis

Namespace: NanoLanguage

BlochState(
configuration,
quantum_number,
spin,
k_point
)

Description

A class for calculating blochstates.

BlochState Arguments

configuration

The configuration for which the eigenstate should be calculated.

Type: A BulkConfiguration

quantum_number

The quantum number of the desired eigenstate.

Type: integer 0

Default:

spin

The spin to calculate the eigenstate for.

Type: Spin.Up | Spin.Down

Default:


          Spin.Up

k_point

The k-point in fractional coordinates that the Bloch state should be calculated for.

Type: A list containing three floats, e.g. [0.0, 0.5, -0.5].

Default:


          [0,0,0]

BlochState Methods

A BlochState 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 Bloch state.

stream

The stream the Bloch state 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.
spin(): Qurry function for the spin.
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 and save the Bloch state for a gold FCC crystal in a NetCDF file.

# Define lattice
lattice = FaceCenteredCubic(4.08*Angstrom)

# Define elements
elements = [Gold]

# Define coordinates
coordinates = [[2.0, 2.0, 2.0]]*Angstrom

# Set up configuration
bulk_configuration = BulkConfiguration(
    lattice,
    elements,
    coordinates
    )

# Define a a calculator
bulk_configuration.setCalculator(LCAOCalculator())

# Calculate and save the Bloch state with quantum number 0
bloch_state = BlochState(bulk_configuration, quantum_number=5,
                         k_point=[0.0, 0.5, 0.5])
nlsave('bloch_state.nc', bloch_state)

blochstate.py

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

Notes


Eigenstate		MullikenPopulation