multi_sites_combine_charges¶
full name: tenpy.networks.site.multi_sites_combine_charges
parent module:
tenpy.networks.site
type: function
-
tenpy.networks.site.
multi_sites_combine_charges
(sites, same_charges=[])[source]¶ Adjust the charges of the given sites (in place) such that they can be used together.
When we want to contract tensors corresponding to different
Site
instances, these sites need to share a singleChargeInfo
. This function adjusts the charges of these sites such that they can be used together.- Parameters
sites (list of
Site
) – The sites to be combined. Modified in place.same_charges (
[[(int, int|str), (int, int|str), ...], ...]
) – Defines which charges actually are the same, i.e. their quantum numbers are added up. Each charge is specified by a tuple(s, i)= (int, int|str)
, where s gives the index of the site withinsites
and i the index or name of the charge in theChargeInfo
of this site.
- Returns
perms – For each site the permutation performed on the physical leg to sort by charges.
- Return type
list of ndarray
Examples
>>> ferm = SpinHalfFermionSite(cons_N='N', cons_Sz='Sz') >>> spin = SpinSite(1.0, 'Sz') >>> ferm.leg.chinfo is spin.leg.chinfo False >>> print(spin.leg) +1 0 [[-1] 1 [ 1]] 2 >>> multi_sites_combine_charges([ferm, spin], same_charges=[[(0, 'Sz'), (1, 0)]]) [array([0, 1, 2, 3]), array([0, 1])] >>> # no permutations where needed >>> ferm.leg.chinfo is spin.leg.chinfo True >> ferm.leg.chinfo.names ['N', 'Sz'] >>> print(spin.leg) +1 0 [[ 0 -1] 1 [ 0 1]] 2