class kwant.builder.BuilderLead(builder, interface, padding=None)[source]

A lead made from a Builder with a spatial symmetry.


The tight-binding system of a lead. It has to possess appropriate symmetry, and it may not contain hoppings between further than neighboring images of the fundamental domain.

interfacesequence of Site instances

Sequence of sites in the scattering region to which the lead is attached.


The hopping from the scattering region to the lead is assumed to be equal to the hopping from a lead unit cell to the next one in the direction of the symmetry vector (i.e. the lead is ‘leaving’ the system and starts with a hopping).

Every system has an attribute leads, which stores a list of BuilderLead objects with all the information about the leads that are attached.


The tight-binding system of a lead.

interfacelist of Site instances

A sorted list of interface sites.

paddinglist of Site instances

A sorted list of sites that originate from the lead, have the same onsite Hamiltonian, and are connected by the same hoppings as the lead sites.



Return a kwant.builder.InfiniteSystem corresponding to the compressed lead.

The order of interface sites is kept during finalization.

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