kwant.solvers.default.smatrix

kwant.solvers.default.smatrix(sys, energy=0, args=(), out_leads=None, in_leads=None, check_hermiticity=True, *, params=None)[source]

Compute the scattering matrix of a system.

An alias exists for this common name: kwant.smatrix.

Parameters:

sys : kwant.system.FiniteSystem

Low level system, containing the leads and the Hamiltonian of a scattering region.

energy : number

Excitation energy at which to solve the scattering problem.

args : tuple, defaults to empty

Positional arguments to pass to the hamiltonian method. Deprecated in favor of ‘params’ (and mutually exclusive with it).

out_leads : sequence of integers or None

Numbers of leads where current or wave function is extracted. None is interpreted as all leads. Default is None and means “all leads”.

in_leads : sequence of integers or None

Numbers of leads in which current or wave function is injected. None is interpreted as all leads. Default is None and means “all leads”.

check_hermiticity : bool

Check if the Hamiltonian matrices are Hermitian. Enables deduction of missing transmission coefficients.

params : dict, optional

Dictionary of parameter names and their values. Mutually exclusive with ‘args’.

Returns:

output : SMatrix

See the notes below and SMatrix documentation.

Notes

This function can be used to calculate the conductance and other transport properties of a system. See the documentation for its output type, SMatrix.

The returned object contains the scattering matrix elements from the in_leads to the out_leads as well as information about the lead modes.

Both in_leads and out_leads must be sorted and may only contain unique entries.

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