# [latest]¶

## Release Notes¶

This release contains a major update of the documentation, which is now hosted by “Read the Docs” at https://tenpy.readthedocs.io/. Update your bookmark :-)

Apart from that, this release introduces a format how to save and load data (in particular TeNPy classes) to HDF5 files. See Saving to disk: input/output for more details. To use that feature, you need to install the h5py package (and therefore some version of the HDF5 library). This is easy with anaconda, conda install h5py, but might be cumbersome on your local computing cluster. (However, many university computing clusters have some version of HDF5 installed already. Check with your local sysadmin.)

## Changelog¶

### Backwards incompatible changes¶

• Don’t save H_MPO_graph as model attribute anymore - this also wasn’t documented.

### Changed¶

• DEFAULT DMRG paramter 'diag_method' from 'lanczos' to 'default', which is the same for large bond dimensions, but performs a full exact diagonalization if the effective Hamiltonian has small dimensions. The threshold introduced is the new DMRG parameter 'max_N_for_ED'.

• Derive the following classes (and their subclasses) from the new Hdf5Exportable to support saving to HDF5: - Site - Terms - OnsiteTerms - CouplingTerms - Model, i.e., all model classes.

### Fixed¶

• Adjust the default DMRG parameter min_sweeps if chi_list is set.

• Avoid some unnecessary transpositions in MPO environments for MPS sweeps (e.g. in DMRG).

• LegPipe did not initialize self.bunched correctly.