full name: tenpy.models.spins_nnn
Spin-S sites coupled by (next-)nearest neighbour interactions on a GroupedSite.
Spin-S sites coupled by next-nearest neighbour interactions.
Next-Nearest-neighbour spin-S models.
Uniform lattice of spin-S sites, coupled by next-nearest-neighbour interactions.
We have two variants implementing the same hamiltonian.
SpinChainNNN uses the
GroupedSite to keep it a
NearestNeighborModel suitable for TEBD,
SpinChainNNN2 just involves longer-range couplings in the MPO.
The latter is preferable for pure DMRG calculations and avoids having to add each of the short
range couplings twice for the grouped sites.
Note that you can also get a
NearestNeighborModel for TEBD from the
latter by using
An example for such a case is given in the file