tightbinder.observables.TransportDevice#

class TransportDevice(system, left_lead, right_lead, period, mode='default')[source]#

Bases: object

Constructor of TransportDevice class to model a transport setup.

Parameters:

  • system (System) – System to compute transmission

  • left_lead (Union[List, ndarray]) – Unit cell of left lead. Array or list where each row contains the position and chemical species of each atom of the lead.

  • right_lead (Union[List, ndarray]) – Same as left lead.

  • period (Union[List, float]) – Distance between consecutive lead unit cells. If given one value, it is used for both right and left leads. If given a list with two values, the first one specifies left period, and second one the right period.

  • mode (str) – Either “default” or “direct”. Default mode uses the SK configuration to establish the system-leads bonds, the intra-lead and the lead-lead bonds. Intended to be used with crystalline or quasicrystalline situations (neighbour based search). Direct mode instead connects the leads to the system straight: each atom of the lead has only one bond (the first found) to the system. The intra-lead and lead-lead bonds are determined using the SK configuration. Intended to be used with amorphous systems (radius based search).

Methods

conductance

Routine to compute the conductance at zero temperature in equilibrium.

transmission

Function to compute the transmission function T(E) of a system.

visualize_device

Routine to visualize the device.
conductance(delta=1e-07, method='LS')[source]#

Routine to compute the conductance at zero temperature in equilibrium.

Parameters:

  • delta (float) – Value of broadening used in Green’s functions. Defaults to 1E-7.

  • method (str) – Method to convergence the self-energies of the leads. Options are ‘LS’ (Lopez Sancho method) and ‘LM’ (Linear Mixing). Defaults to ‘LS’.

Return type:

float

Returns:

Value of conductance.

transmission(minE, maxE, npoints=100, delta=1e-07, method='LS')[source]#

Function to compute the transmission function T(E) of a system. One has to specify the unit cell of each lead in terms of the positions and chemical species. Only two terminal setups are allowed. The lead-system coupling and the lead-lead coupling are computed using the corresponding Slater-Koster amplitudes.

Parameters:

  • minE (float) – Minimum value of energy window where the transmission is computed.

  • maxE (float) – Maximum value of energy window.

  • npoints (int) – Sampling of energy window. Defaults to 100.

  • delta (float) – Value of broadening used in Green’s functions. Defaults to 1E-7.

  • method (str) – Method to convergence the self-energies of the leads. Options are ‘LS’ (Lopez Sancho method) and ‘LM’ (Linear Mixing). Defaults to ‘LS’.

Return type:

Tuple[List, List]

Returns:

List of transmission values and energy window.

visualize_device(ax=None, pbc=False)[source]#

Routine to visualize the device. Intended to be used only with two dimensional (planar) systems.

Parameters:

  • ax (Axes) – Axis object to plot the device on.

  • pbc (bool) – Boolean to toggle 3d plot of the device in case the system and the leads have PBC.

Return type:

None