kwant.wraparound.wraparound(builder, keep=None, *, coordinate_names='xyz')[source]

Replace translational symmetries by momentum parameters.

A new Builder instance is returned. By default, each symmetry is replaced by one scalar momentum parameter that is appended to the already existing arguments of the system. Optionally, one symmetry may be kept by using the keep argument. The momentum parameters will have names like ‘k_n’ where the ‘n’ are specified by ‘coordinate_names’.

keepint, optional

Which (if any) translational symmetry to keep.

coordinate_namessequence of strings, default: ‘xyz’

The names of the coordinates along the symmetry directions of ‘builder’.


Wraparound is stop-gap functionality until Kwant 2.x which will include support for higher-dimension translational symmetry in the low-level system format. It will be deprecated in the 2.0 release of Kwant.

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4.5. kwant.wraparound – Wrapping around translational symmetries

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