:mod:`kwant.system` -- Low-level interface of systems
*****************************************************

.. automodule:: kwant.system

This module is the binding link between constructing tight-binding systems and
doing calculations with these systems.  It defines the interface which any
problem-solving algorithm should be able to access, independently on how the
system was constructed.  This is achieved by using python abstract base classes
(ABC) -- classes, which help to ensure that any derived classes implement the
necessary interface.

Any system which is provided to a solver should be derived from the appropriate
class in this module, and every solver can assume that its input corresponds to
the interface defined here.

In practice, very often Kwant systems are finalized
`builders <kwant.builder.Builder>` (i.e.
`kwant.builder.FiniteSystem` or `kwant.builder.InfiniteSystem`) and offer some
additional attributes.

.. autosummary::
   :toctree: generated/

   System
   InfiniteSystem
   FiniteSystem
   PrecalculatedLead