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DeviceConfiguration |  |
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| BulkConfiguration | NanoSheet |
DeviceConfiguration — Class for representing a structure coupled with semi-infinite bulk, i.e. one-probe, two-probe, etc.
Construction of the device configuration class. The DeviceConfiguration is formed from a central region given as BulkConfiguration, and one or more electrodes given as BulkConfiguration(s) as well.
The central described as a BulkConfiguration.
Type: A BulkConfiguration.
Electrodes of the device given as a BulkConfiguration or a sequence of BulkConfiguration's. If there is only one given one-electrode it is considered a one-probe. If two electrodes are given, the device is considered a two-probe, with the first considered to the left electrode, and the second the right electrode. If three electrodes are given, it is considered a three-probe, where the third electrode is the gate electrode.
Type: A list of BulkConfiguration's.
A DeviceConfiguration object provides the following methods:
addTags(tags, indices): Add a set of tags to atoms matching a collection of indices.
bravaisLattice(): Method for getting the Bravais lattice of the central region
calculator(): Return the calculator attached to the configuration, i.e. the calculator that will
be used for both simulation and analysis.
cartesianCoordinates(): The Cartesian coordinates of the atoms.
centralRegion(): Method for obtaining the central region of a DeviceConfiguration
dielectricRegions(): Method for getting the dielectric regions of the central region.
electrodes(): Method for obtaining the electrode BulkConfiguration of a DeviceConfiguration
electrodesDisplacement(): Method for obtaining the displacement of the BravaisLattice of the electrodes in the C-direction in order to match the BravaisLattice of the
central_region
elements(): Method for getting the elements of the central region.
externalPotential(): Method for obtaining the external potential on the central region.
fractionalCoordinates(): Method for obtaining the fractional coordinates of the central configuration atoms.
ghostAtoms(): Method for getting the list of ghost atom indices for the central region.
indicesFromTags(tags): List the indices associated with a given collection of tags.
metallicRegions(): Method for getting the metallic regions of the central region.
nlprint(stream, name): Print a string containing an ASCII description of the DeviceConfiguration.
removeTags(tags, indices, purge): Remove a set of tags from atoms matching a collection of indices.
setCalculator(calculator, initial_state, initial_spin): Attach a Calculator class to the configuration which will be used in calculations
involving the configuration.
The Calculator object that should be attached to the configuration.
Type: DeviceHuckelCalculator | DeviceLCAOCalculator
Default:
None
The initial state to be used for this configuration.
Type: DeviceConfiguration with an attached calculator.
Default:
None
The InitialSpin object to be used for this configuration.
Type: InitialSpin | None
Default:
None for calculators not supporting spin. Maximally spin-polarized for calculators supporting spin.
setDielectricRegions(dielectric_regions): Set the dielectric regions of the central region.
setExternalPotential(external_potential): Set the external potential on the central region.
Type: AtomicShift
setMetallicRegions(metallic_regions): Set the metallic regions of the central region
setVelocities(velocities): Function to set velocities on the configuration.
symbols(): The element symbols of the configuration.
tags(indices): List the tags associated with a given collection of indices.
update(force_restart): Using the configurations set calculator, a self-consistent solution is generated.
velocities(): The velocities of the atoms.
Construct a device system consisting of a hydrogen molecule connected with two chains of Lithium atoms.
# Define A,B directions of lattice
vector_a = [5.0, 0.0, 0.0]*Angstrom
vector_b = [0.0, 5.0, 0.0]*Angstrom
# setup electrode
electrode = BulkConfiguration(
bravais_lattice=UnitCell(vector_a, vector_b,
[0.0, 0.0, 9.0]*Angstrom),
elements=[Lithium, Lithium, Lithium],
cartesian_coordinates=[[ 2.5, 2.5, 1.5],
[ 2.5, 2.5, 4.5],
[ 2.5, 2.5, 7.5]]*Angstrom
)
# setup Central region
central_region = BulkConfiguration(
bravais_lattice= UnitCell(vector_a, vector_b,
[0.0, 0.0, 22.0]*Angstrom),
elements=[Lithium, Lithium, Lithium, Hydrogen, Hydrogen,
Lithium, Lithium, Lithium],
cartesian_coordinates=[[ 2.5, 2.5, 1.5],
[ 2.5, 2.5, 4.5],
[ 2.5, 2.5, 7.5],
[ 2.5, 2.5, 10.5],
[ 2.5, 2.5, 11.5],
[ 2.5, 2.5, 14.5],
[ 2.5, 2.5, 17.5],
[ 2.5, 2.5, 20.5]]*Angstrom
)
#setup Device configuration
device_configuration = DeviceConfiguration(
central_region,
[electrode, electrode]
)
The setup of device configurations with two electrodes
A device system with two electrodes is created by placing two electrode BulkConfiguration to the left and the right of of a central BulkConfiguration. The properties within the electrode regions are fixed at their bulk properties, while the central region of the device configuration is described self-consistently. The device configuration must fulfill the following properties:
The electrodes and the central BulkConfiguration must have the same cell vectors in the A and B direction.
The C direction must be perpendicular to the A and B directions.
If the left A-B face of the central unit cell is aligned with the left A-B face of the left electrode, the first atoms in the central unit cell must be identical with the atoms in the left electrode. See Figure 5 for an example.
If the right A-B face of the central unit cell is aligned with the right A-B face of the right electrode, the last atoms in the central unit cell must be identical with the atoms in the right electrode. See Figure 5 for an example.
Figure 5: Upper panel: Example for the constituents of a device system with 2 electrodes. The constituents are Left Electrode, Central Region, Right Electrode. Note that the first atoms in the central region must be positioned identical to the atoms in the left electrode. Similarly, the last atoms in the central region must be positioned relative to the right face of the unit cell, identical to the atoms in the right electrode. Lower panel: The (periodically-repeated) two-probe system. The unit cell of the central region is indicated with dashed lines while the unit cells of the electrodes are indicated by solid lines.
Vacuum basis sets (ghost atoms) can be included in the DeviceConfiguration, by specifying a ghost_atoms list for the BulkConfiguration of the central and electrode regions.
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| BulkConfiguration |
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NanoSheet |