1) The sys in an SU(N) SpinWaveTheory is now transformed directly instead of allocating and storing a bunch of rotated operators in SWTDataSUN. In particular, all interactions are converted into general interactions (tensor decomposition), and the scalar, bilin, biquad fields of a PairCoupling are set to zero. The operators in the tensor decomposition are then transformed into the local reference frames directly in the interactions_union of the sys.
2) The index corresponding to the condensed boson has been shifted from 1 to N. (This simplifies indexing somewhat.)
3) The functions multiply_by_hamiltonian_dipole! and multiply_by_hamiltonian_SUN! have been added. These multiply a given vector by the Hamiltonian without first constructing a dense Hamiltonian matrix. This takes advantage of sparsity. Both functions demonstrate linear scaling with the number of atoms in the magnetic supercell.
4) reshapes are used to take advantage of Julia's indexing facilities (instead of manual index offsets).
1) The
sysin an SU(N)SpinWaveTheoryis now transformed directly instead of allocating and storing a bunch of rotated operators inSWTDataSUN. In particular, all interactions are converted intogeneralinteractions (tensor decomposition), and thescalar,bilin,biquadfields of aPairCouplingare set to zero. The operators in the tensor decomposition are then transformed into the local reference frames directly in theinteractions_unionof thesys.2) The index corresponding to the condensed boson has been shifted from 1 to N. (This simplifies indexing somewhat.)
3) The functions
multiply_by_hamiltonian_dipole!andmultiply_by_hamiltonian_SUN!have been added. These multiply a given vector by the Hamiltonian without first constructing a dense Hamiltonian matrix. This takes advantage of sparsity. Both functions demonstrate linear scaling with the number of atoms in the magnetic supercell.4)
reshapes are used to take advantage of Julia's indexing facilities (instead of manual index offsets).