main_smaller.jl

using MPSKit,TensorKit,SUNRepresentations

let
    #another labeling scheme
    su3_irrep(m, n) = SUNRepresentations.SUNIrrep((m + n, n, 0))

    function su3_heis_ham(m::Int, n::Int, J::Number = 1.0, E₀::Number = 0.0)
        # Hamiltonian for the SU(3) Heisenberg model
        #   H = J ∑ (Sᵢ•Sⱼ) + E₀
        #   where the S are the SU(3) generators, normalised such that tr(SᵃSᵇ) = 15//2 δᵃᵇ.

        physical_space = RepresentationSpace(su3_irrep(m, n) => 1)
        adjoint_space  = RepresentationSpace(su3_irrep(1, 1) => 1)
        trivial_space  = RepresentationSpace(su3_irrep(0, 0) => 1)

        Sᵢ = TensorMap(ones, ComplexF64, trivial_space * physical_space, adjoint_space * physical_space) * sqrt(6)
        Sⱼ = TensorMap(ones, ComplexF64, adjoint_space * physical_space, trivial_space * physical_space) * sqrt(6)

        mpo_data = Array{Any, 3}(missing, 1, 3, 3)
        mpo_data[1,1,1] = 1.0
        mpo_data[1,3,3] = 1.0

        mpo_data[1,1,2] = J * permute(Sᵢ,(1,2),(4,3))
        mpo_data[1,2,3] = permute(Sⱼ,(1,2),(4,3));
        mpo_data[1,1,3] = E₀

        return MPOHamiltonian(mpo_data)

    end

    H = su3_heis_ham(3,0,2,3);

    gs = InfiniteMPS([RepresentationSpace(su3_irrep(3,0) => 1)],
        [Rep[SU{3}]((0, 0, 0)=>1, (2, 1, 0)=>3, (3, 0, 0)=>2, (3, 3, 0)=>2, (4, 2, 0)=>5, (5, 1, 0)=>1, (5, 4, 0)=>1, (6, 3, 0)=>2)]);
    (gs,env) = find_groundstate(gs,H,Vumps(maxiter=1));
end