This PR introduces a general and flexible subspace expansion interface.
This allows users to perform a 2-site expansion alongside other (typically 1-site) routines, which has better scaling both in the bond dimension and the local Hilbertspace dimension than their 2-site analogs.
The expansion works on general tree structures and can be seamlessly incorporated into existing algorithms by composing and chaining different local updaters via the compose_updaters function.
Keyword arguments like maxdim and cutoff inside of expander_kwargs can be used to modify parameters specific to the expansion. Furthermore, a general, randomized svd-routine has been implemented, which can be used for the expansion and allows for the favorable, aforementioned scaling.
An example script can be found in the test folder.
This PR introduces a general and flexible subspace expansion interface.
This allows users to perform a 2-site expansion alongside other (typically 1-site) routines, which has better scaling both in the bond dimension and the local Hilbertspace dimension than their 2-site analogs.
The expansion works on general tree structures and can be seamlessly incorporated into existing algorithms by composing and chaining different local updaters via the
compose_updatersfunction. Keyword arguments likemaxdimandcutoffinside ofexpander_kwargscan be used to modify parameters specific to the expansion. Furthermore, a general, randomized svd-routine has been implemented, which can be used for the expansion and allows for the favorable, aforementioned scaling.An example script can be found in the test folder.