Solvers

function eig_solver(env, phi0::ITensor, time_step::Nothing; kwargs...)

Solver to find smallest eigenvalue corresponding to "matrix" env and input vector phi0.

Named arguments for solver and their default values:

See the documentation of KrylovKit.jl.

• ishermitian::Bool = true
• solver_tol::Float64 = 1E-14.
• solver_krylovdim::Int = 5.
• solver_maxiter::Int = 2.
• solver_outputlevel::Int = 0: See verbosity in KrylovKit.jl.
• solver_eager::Bool = false.
• solver_check_convergence::Bool = false.

Return values:

• ::Union{Float64, ComplexF64}: Eigenvalue.
• ::ITensor: Eigenstate corresponding to the eigenvalue.

function exp_solver(env, phi0::ITensor, time_step::Union{Float64, ComplexF64}; kwargs...)

Exponentiation solver to find exp(env * phi0 * time_step).

Named arguments for solver and their default values:

See the documentation of KrylovKit.jl.

• ishermitian::Bool = true
• solver_tol::Float64 = 1E-12.
• solver_krylovdim::Int = 30.
• solver_maxiter::Int = 10.
• solver_outputlevel::Int = 0: See verbosity in KrylovKit.jl.
• solver_eager::Bool = true.
• solver_check_convergence::Bool = true.

Return values:

• ::Float64: NaN.
• ::ITensor: Exponentiated ITensor.