[0.7.0] - 2020-09-04

Release Notes

The big new feature is the implementation of the W_I and W_II method for approximating exponentials of an MPO with an MPO, and MPS compression / MPO application to an MPS, to allow time evolution with ExpMPOEvolution().


Backwards incompatible changes

  • Remove argument leg0 from build_MPO.

  • Remove argument leg0 from from_grids, instead optionally give all legs as argument.

  • Moved/renamed the module tenpy.algorithms.mps_sweeps to tenpy.algorithms.mps_common. The old mps_sweeps still exists for compatibility, but raises a warning upon import.

  • Moved/renamed the module tenpy.algorithms.purification_tebd to tenpy.algorithms.purification (for the PurificaitonTEBD and PurificationTEBD2) and tenpy.algorithms.disentangler (for the disentanglers).



  • By default, for an usual MPO define IdL and IdR on all bonds. This can generate “dead ends” in the MPO graph of finite systems, but it is useful for the make_WI/make_WII for MPO-exponentiation.

  • tenpy.models.lattice.Lattice.plot_basis() now allows to shade the unit cell and shift the origin of the plotted basis.

  • Don’t use bc_shift in tenpy.models.lattice.Lattice.plot_couplings() any more - it lead to confusing figures. Instead, the new keyword wrap=True allows to directly connect all sites. This is done to avoid confusing in combination with plot_bc_identified().

  • Error handling of non-zero qtotal for TransferMatrix.