Parameters for calculating conductance
Parameters here are for calculating conductance of the device.
calculation.conductance.method
keyword: calculation.conductance.method
possible values: ‘GreenFunction’, ‘WaveFunction’
default value: ‘GreenFunction’
description: method used for calculating conductance
an example:
calculation.conductance.method = 'GreenFunction'
calculation.conductance.leadPairs
keyword: calculation.conductance.leadPairs
possible values: cell array of 1 x 2 integer array
default value: all pairs of leads
description: For each pair of leads in the cell, the conductance from the first lead of the pair to second lead will be calculated.
an example:
calculation.conductance.leadPairs = {[1,2], [2,1]}
calculation.conductance.kSpaceGridNumber
keyword: calculation.conductance.kSpaceGridNumber
possible values: 3 x 1 integer array
default value: the value of calculation.k_spacegrids.number which was used in the Hamiltonian calculation, or [1 1 1] if an user provided Hamiltonian is used.
description: number of small k-space grids in each direction which, together with kSpaceGridShift, are used to produce the parameter kSpacePoints.
an example:
calculation.conductance.kSpaceGridNumber = [10 10 10]'
calculation.conductance.kSpaceGridShift
keyword: calculation.conductance.kSpaceGridShift
possible values: 3 x 1 or 1 x 3 array, [s_1, s_2, s_3], with each s_i a double number between 0 and 1.
default value: if the conductance.kSpaceGridNumber is given, or if an user provided Hamiltonian is used, the default value is [0 0 0], otherwise the default value is the value of calculation.k_spacegrids.shift which was used in the Hamiltonian calculation.
description: k-space grid point shift. While all s_i are set to be 0, the Gamma point is always among the k-space grid points being generated; otherwise, the k-space grid points will be shifted s_1, s_2, and s_3 grid lengths along their grid vector directions, respectively.
an example:
calculation.conductance.kSpaceGridShift = [1/2 1/2 1/2]'
calculation.conductance.numberOfEnergyPoints
keyword: calculation.conductance.numberOfEnergyPoints
possible values: an integer number
default value: determined by parameter energyInterval
description: the number of energy points used in the energy space integration. This is only used when the energyPoints and energyPointWeights are not given explicitly.
an example:
calculation.conductance.numberOfEnergyPoints = 100
calculation.conductance.energyInterval
keyword: calculation.conductance.energyInterval
possible values: a double number
default value: 5e-2 eV
description: Energy interval used to determine the parameter numberOfEnergyPoints.
an example:
calculation.conductance.energyInterval = 1e-3
calculation.conductance.eta
keyword: calculation.conductance.eta
possible values: a small double number
default value: no default value
description: the small eta used in the calculation of self-energy and/or Green’s function when the ‘GreenFunction’ method is chosen. This parameter is only used when the parameter conductance.etaSigma and/or conductance.etaGF is not given.
an example:
calculation.conductance.eta = 1e-4
calculation.conductance.epsilon
keyword: calculation.conductance.epsilon
possible values: a small double number
default value: 1e-9
description: used as a criterion of Bloch wave. For a wave with wave-vector k, if ||exp(ika)|-1| < epsilon, where a is unit cell length, it is considered as a Bloch wave; otherwise it is considered as an evanescent wave.
an example:
calculation.conductance.epsilon = 1e-4