[0.4.1] - 2019-08-14

Backwards incompatible changes

• Switch the sign of the BoseHubbardModel and FermiHubbardModel to hopping and chemical potential having negative prefactors. Of course, the same adjustment happens in the BoseHubbardChain and FermiHubbardChain.

• moved BoseHubbardModel and BoseHubbardChain as well as FermiHubbardModel and FermiHubbardChain into the new module tenpy.models.hubbard.

• Change arguments of coupling_term_handle_JW() and multi_coupling_term_handle_JW() to use strength and sites instead of op_needs_JW.

• Only accept valid identifiers as operator names in add_op().

Changed

• grid_concat() allows for None entries (representing zero blocks).

• from_full() allows for ‘segment’ boundary conditions.

• apply_local_op() allows for n-site operators.

Added

• max_range attribute in MPO and MPOGraph.

• is_hermitian()

• Nearest-neighbor interaction in BoseHubbardModel

• multiply_op_names() to replace ' '.join(op_names) and allow explicit compression/multiplication.

• order_combine_term() to group operators together.

• dagger() of MPO’s (and to implement that also flip_charges_qconj()).

• has_label() to check if a label exists

• qr_li() and rq_li()

• Addition of MPOs

• 3 additional examples for chern insulators in examples/chern_insulators/.

• FermionicHaldaneModel and BosonicHaldaneModel.

• from_MPOModel() for initializing nearest-neighbor models after grouping sites.

Fixed

• issue #36: long-range couplings could give IndexError.

• issue #42: Onsite-terms in FermiHubbardModel were wrong for lattices with non-trivial unit cell.

• Missing a factor 0.5 in GUE().

• Allow TermList to have terms with multiple operators acting on the same site.

• Allow MPS indices outside unit cell in mps2lat_idx() and lat2mps_idx().

• expectation_value() did not work for n-site operators.