kwant.solvers.common.SMatrix(data, lead_info, out_leads, in_leads, current_conserving=False)¶Bases: kwant.solvers.common.BlockResult
A scattering matrix.
Transport properties can be easily accessed using the
transmission method (don’t be fooled by the name,
it can also compute reflection, which is just transmission from one
lead back into the same lead.)
SMatrix however also allows for a more direct access to the result: The
data stored in SMatrix is a scattering matrix with respect to lead modes
and these modes themselves. The details of this data can be directly
accessed through the instance variables data and lead_info. Subblocks
of data corresponding to particular leads are conveniently obtained by
submatrix.
Attributes
| data | (NumPy array) a matrix containing all the requested matrix elements of the scattering matrix. |
| lead_info | (list of data) a list containing kwant.physics.PropagatingModes for each lead. |
| out_leads, in_leads | (sequence of integers) indices of the leads where current is extracted (out) or injected (in). Only those are listed for which SMatrix contains the calculated result. |
Methods
block_coords(lead_out, lead_in)¶Return slices corresponding to the block from lead_in to lead_out.
conductance_matrix()¶Return the conductance matrix.
This is the matrix 
such that 
where 
and 
are, respectively, the vectors of currents and voltages
for each lead.
This matrix is useful for calculating non-local resistances. See Section 2.4 of the book by S. Datta.
in_block_coords(lead_in)¶Return a slice with the columns in the block corresponding to lead_in.
num_propagating(lead)¶Return the number of propagating modes in the lead.
out_block_coords(lead_out)¶Return a slice with the rows in the block corresponding to lead_out.
submatrix(lead_out, lead_in)¶Return the matrix elements from lead_in to lead_out.
transmission(lead_out, lead_in)¶Return transmission from lead_in to lead_out.
If the option current_conserving has been enabled for this object,
this method will deduce missing transmission values whenever possible.
Current conservation is enabled by default for objects returned by
smatrix and
greens_function whenever the Hamiltonian has
been verified to be Hermitian (option check_hermiticity, enabled by
default).