ExactDiagonalization

const basicoptions = (
    nev = "number of eigenvalues to be computed",
    which = "type of eigenvalues to be computed",
    tol = "tolerance of the computation",
    maxiter = "maximum iteration of the computation",
    v₀ = "initial state",
    krylovdim = "maximum dimension of the Krylov subspace that will be constructed",
    verbosity = "verbosity level"
)

Basic options of actions for exact diagonalization method.

const edtimer = TimerOutput()

Default shared timer for all exact diagonalization methods.

const Abelian = AbelianQuantumNumber

Type alias for AbelianQuantumNumber.

Abelian(bs::AbelianBases)

Get the Abelian quantum number of a set of spin bases.

Abelian(bs::BinaryBases)

Get the Abelian quantum number of a set of binary bases.

AbelianBases{A<:Abelian, N} <: Sector

A set of Abelian bases, that is, a set of bases composed from the product of local Abelian Graded spaces.

To improve the efficiency of the product of local Abelian Graded spaces, we adopt a two-step strategy:

1. partition the local spaces into several groups in each of which the local spaces are direct producted and rearranged according to the Abelian quantum numbers, and then
2. glue the results obtained in the previous step so that a sector with a certain Abelian quantum number can be targeted.

In principle, a binary-tree strategy can be more efficient, but our two-step strategy is enough for a quantum system that can be solved by the exact diagonalization method.

The partition of the local Abelian Graded spaces is assigned by a NTuple{N, Vector{Int}}, with each of its element contains the sequences of the grouped local spaces specified by a table.

AbelianBases(locals::AbstractVector{Int}, partition::NTuple{N, AbstractVector{Int}}=partition(length(locals))) where N

Construct a set of spin bases that subjects to no quantum number conservation.

AbelianBases(locals::Vector{Graded{A}}, quantumnumber::A, partition::NTuple{N, AbstractVector{Int}}=partition(length(locals))) where {N, A<:Abelian}

Construct a set of spin bases that preserves a certain symmetry specified by the corresponding Abelian quantum number.

AbelianGradedSpace(quantumnumbers::AbstractVector{<:AbelianQuantumNumber}, dimensions::AbstractVector{<:Integer}, dual::Bool=false; ordercheck::Bool=false, duplicatecheck::Bool=false, degeneracycheck::Bool=false)

Construct an Abelian graded space.

Here:

• quantumnumbers specifies the Abelian quantum numbers labeling the irreducible representations of the corresponding Abelian group which must be sorted in the ascending order. Such an ordering should be manually guaranteed by the user. When and only when the keyword argument ordercheck is true, the constructor will check whether this condition is satisfied and raise an error if it doesn't. Besides, quantumnumbers must not contain duplicate Abelian quantum numbers, manually guaranteed by the user as well. This condition can be checked when and only when both ordercheck==true and duplicatecheck==true. An error will be raised if this check fails.
• dimensions specifies the degenerate dimensions of the corresponding Abelian quantum numbers. Apparently, each degenerate dimension must be positive, which should also be manually guaranteed by the user. When and only when the keyword argument degeneracycheck is true, the constructor will check whether this condition is satisfied and raise an error if it doesn't.
• dual specifies whether the graded space is the dual representation of the corresponding Abelian group, which roughly speaking, can be viewed as the direction of the arrow of the Abelian quantum numbers labeling the irreducible representations. We assume dual==true corresponds to the in-arrow and dual==false corresponds to the out-arrow.

AbelianGradedSpace{QN<:AbelianQuantumNumber} <: RepresentationSpace{QN}

A quantum representation space of an Abelian group that has been decomposed into the direct sum of its irreducible representations.

AbelianGradedSpace(pairs; dual::Bool=false)
AbelianGradedSpace(pairs::Pair...; dual::Bool=false)
AbelianGradedSpace{QN}(pairs; dual::Bool=false) where {QN<:AbelianQuantumNumber}
AbelianGradedSpace{QN}(pairs::Pair...; dual::Bool=false) where {QN<:AbelianQuantumNumber}

Construct an Abelian graded space.

In this function, the Abelian quantum numbers will be sorted automatically, therefore, their orders need not be worried. Duplicate and dimension checks of the quantum numbers are also carried out and errors will be raised if either such checks fails.

AbelianGradedSpaceProd{N, QN<:AbelianQuantumNumber} <: CompositeAbelianGradedSpace{N, QN}

Direct product of Abelian graded spaces.

AbelianGradedSpaceSum{N, QN<:AbelianQuantumNumber} <: CompositeAbelianGradedSpace{N, QN}

Direct sum of Abelian graded spaces.

AbelianQuantumNumber

Abstract type of Abelian quantum numbers.

An Abelian quantum number is the label of a irreducible representation of an Abelian group acted on a quantum representation space.

AbelianQuantumNumberProd{T<:Tuple{Vararg{SimpleAbelianQuantumNumber}}} <: AbelianQuantumNumber

Deligne tensor product of simple Abelian quantum numbers.

AbelianQuantumNumberProd(contents::SimpleAbelianQuantumNumber...)
AbelianQuantumNumberProd(contents::Tuple{Vararg{SimpleAbelianQuantumNumber}})

Construct a Deligne tensor product of simple Abelian quantum numbers.

AbelianQuantumNumberProd{T}(vs::Vararg{Number, N}) where {N, T<:NTuple{N, SimpleAbelianQuantumNumber}}
AbelianQuantumNumberProd{T}(vs::NTuple{N, Number}) where {N, T<:NTuple{N, SimpleAbelianQuantumNumber}}

Construct a Deligne tensor product of simple Abelian quantum numbers by their values.

AbstractGreenFunction{T<:Number} <: Function

Abstract type for Green's functions obtained by Krylov space expansion.

(gf::AbstractGreenFunction)(ω::Number; sign::Bool=false) -> Matrix{promote_type(typeof(ω), eltype(gf))}

Get the values of an AbstractGreenFunction at ω.

When sign is true, the opposite will be taken in the result.

BinaryBases{A<:Abelian, B<:BinaryBasis, T<:AbstractVector{B}} <: Sector

A set of binary bases.

BinaryBases(spindws, spinups, spinfulparticle::Abelian[ℕ ⊠ 𝕊ᶻ])
BinaryBases(spindws, spinups, spinfulparticle::Abelian[𝕊ᶻ ⊠ ℕ])

Construct a set of binary bases that preserves both the particle number and the spin z-component conservation.

BinaryBases(spindws, spinups, sz::𝕊ᶻ)

Construct a set of binary bases that preserves the spin z-component but not the particle number conservation.

BinaryBases(states, particle::ℕ)
BinaryBases(nstate::Integer, particle::ℕ)

Construct a set of binary bases that preserves the particle number conservation.

BinaryBases(states)
BinaryBases(nstate::Integer)

Construct a set of binary bases that subjects to no quantum number conservation.

BinaryBasis{I<:Unsigned}

Binary basis represented by an unsigned integer.

Here, we adopt the following common rules:

1. In a binary basis, a bit of an unsigned integer represents a single-particle state that can be occupied (1) or unoccupied (0).
2. The position of this bit in the unsigned integer counting from the right corresponds to the sequence of the single-particle state specified by a table.
3. When representing a many-body state by creation operators, they are arranged in ascending order according to their sequences.

In this way, any many-body state of canonical fermionic or hardcore bosonic systems can be represented ambiguously by the binary bases, e.g., $c^†_2c^†_3c^†_4|\text{Vacuum}\rangle$ is represented by $1110$.

BinaryBasis(states; filter=index->true)
BinaryBasis{I}(states; filter=index->true) where {I<:Unsigned}

Construct a binary basis with the given occupied states.

BinaryBasisRange{I<:Unsigned} <: VectorSpace{BinaryBasis{I}}

A continuous range of binary basis from 0 to 2^n-1.

CompositeAbelianGradedSpace{N, QN<:AbelianQuantumNumber} <: RepresentationSpace{QN}

Abstract type of composite Abelian graded spaces.

ED(
    lattice::AbstractLattice, hilbert::Hilbert, terms::OneOrMore{Term}, boundary::Boundary=plain, dtype::Type{<:Number}=valtype(terms);
    neighbors::Union{Int, Neighbors}=nneighbor(terms)
)
ED(
    lattice::AbstractLattice, hilbert::Hilbert, terms::OneOrMore{Term}, table::AbstractDict, sectors::OneOrMore{Sector}=Sector(hilbert; table=table), boundary::Boundary=plain, dtype::Type{<:Number}=valtype(terms);
    neighbors::Union{Int, Neighbors}=nneighbor(terms)
)

Construct the exact diagonalization method for a quantum lattice system.

ED(system::Generator{<:Operators}, table::AbstractDict, sectors::OneOrMore{Sector}, dtype::Type{<:Number}=scalartype(system))
ED(lattice::Union{AbstractLattice, Nothing}, system::Generator{<:Operators}, table::AbstractDict, sectors::OneOrMore{Sector}, dtype::Type{<:Number}=scalartype(system))

Construct the exact diagonalization method for a quantum lattice system.

ED(
    lattice::AbstractLattice, hilbert::Hilbert, terms::OneOrMore{Term}, quantumnumbers::OneOrMore{Abelian}, boundary::Boundary=plain, dtype::Type{<:Number}=valtype(terms);
    neighbors::Union{Int, Neighbors}=nneighbor(terms)
)
ED(
    lattice::AbstractLattice, hilbert::Hilbert, terms::OneOrMore{Term}, table::AbstractDict, quantumnumbers::OneOrMore{Abelian}, boundary::Boundary=plain, dtype::Type{<:Number}=valtype(terms);
    neighbors::Union{Int, Neighbors}=nneighbor(terms)
)

Construct the exact diagonalization method for a quantum lattice system.

ED{K<:EDKind, L<:Union{AbstractLattice, Nothing}, S<:Generator{<:Operators}, M<:EDMatrixization, H<:CategorizedGenerator{<:OperatorSum{<:EDMatrix}}} <: Frontend

Exact diagonalization method of a quantum lattice system.

EDEigen{S<:Tuple{Vararg{Union{Abelian, Sector}}}} <: Action

Eigen system by exact diagonalization method.

EDEigen(sectors::Union{Abelian, Sector}...)
EDEigen(sectors:::Tuple{Vararg{Union{Abelian, Sector}}})

Construct an EDEigen.

EDEigenData{V<:Number, T<:Number, S<:Sector} <: Data

Eigen decomposition in exact diagonalization method.

Compared to the usual eigen decomposition Eigen, EDEigenData contains a :sectors attribute to store the sectors of Hilbert space in which the eigen values and eigen vectors are computed. Furthermore, given that in different sectors the dimensions of the sub-Hilbert spaces can also be different, the :vectors attribute of EDEigenData is a vector of vector instead of a matrix.

EDKind{K}

Kind of the exact diagonalization method applied to a quantum lattice system.

EDKind(::Type{<:FockIndex})

Kind of the exact diagonalization method applied to a canonical quantum Fock lattice system.

EDKind(::Type{<:SpinIndex})

Kind of the exact diagonalization method applied to a canonical quantum spin lattice system.

EDMatrix{M<:SparseMatrixCSC, S<:Sector} <: OperatorPack{M, Tuple{S, S}}

Matrix representation of quantum operators between a ket Hilbert space and a bra Hilbert space.

EDMatrix(m::SparseMatrixCSC, sector::Sector)
EDMatrix(m::SparseMatrixCSC, braket::NTuple{2, Sector})
EDMatrix(m::SparseMatrixCSC, bra::Sector, ket::Sector)

Construct a matrix representation when

1. the bra and ket Hilbert spaces share the same bases;
2. the bra and ket Hilbert spaces may be different;
3. the bra and ket Hilbert spaces may or may not be the same.

EDMatrixization{D<:Number, T<:AbstractDict, S<:Sector} <: Matrixization

Matrixization of a quantum lattice system on a target Hilbert space.

EDMatrixization{D}(table::AbstractDict, sector::S, sectors::S...) where {D<:Number, S<:Sector}
EDMatrixization{D}(table::AbstractDict, brakets::Vector{Tuple{S, S}}) where {D<:Number, S<:Sector}

Construct a matrixization.

const Graded = AbelianGradedSpace

Type alias for AbelianGradedSpace.

Graded{ℤ₁}(spin::Spin)
Graded{𝕊ᶻ}(spin::Spin)

Decompose a local spin space into an Abelian graded space that preserves 1) no symmetry, and 2) spin-z component symmetry.

GreenFunction(
    operators::AbstractVector{<:QuantumOperator}, ed::Algorithm{<:ED}, sign::Bool=false;
    E₀::Union{Real, Nothing}=nothing, Ω::Union{AbstractVector{<:Number}, Nothing}=nothing, sector₀::Union{Sector, Nothing}=nothing, maxdim::Integer=200, kwargs...
)
GreenFunction(
    operators::AbstractVector{<:QuantumOperator}, ed::ED, sign::Bool=false;
    E₀::Union{Real, Nothing}=nothing, Ω::Union{AbstractVector{<:Number}, Nothing}=nothing, sector₀::Union{Sector, Nothing}=nothing, maxdim::Integer=200, timer::TimerOutput=edtimer, kwargs...
)

Construct a GreenFunction.

GreenFunction{T<:Number, V<:Real} <: AbstractGreenFunction{T}

Green function obtained by Krylov space expansion.

(gf::GreenFunction)(dest::AbstractMatrix{<:Number}, ω::Number; sign::Bool=false) -> typeof(dest)

Get the values of a GreenFunction at ω and add the result to dest.

GroundStateExpectation{D<:Number, O<:Array{<:Union{Operator, Operators}}} <: Action

Ground state expectation of operators.

GroundStateExpectationData{A<:Array{<:Number}} <: Data

Data of ground state expectation of operators, including:

values::A: values of the ground state expectation.

RepresentationSpace{QN<:AbelianQuantumNumber} <: VectorSpace{QN}

Abstract type of quantum representation spaces of Abelian groups.

RetardedGreenFunction{T<:Number, V<:Real} <: AbstractGreenFunction{T}

Retarded Green's function obtained by Krylov space expansion.

(gf::RetardedGreenFunction)(dest::AbstractMatrix{<:Number}, ω::Number; sign::Bool=false) -> typeof(dest)

Get the values of a RetardedGreenFunction at ω and add the result to dest.

RetardedGreenFunction(operators::AbstractVector{<:QuantumOperator}, ed::Algorithm{<:ED}, sign::Bool; maxdim::Integer=200, kwargs...)
RetardedGreenFunction(operators::AbstractVector{<:QuantumOperator}, ed::ED, sign; maxdim::Integer=200, timer::TimerOutput=edtimer, kwargs...)

Construct a RetardedGreenFunction.

Sector(hilbert::Hilbert{<:Spin}, partition::Tuple{Vararg{AbstractVector{Int}}}=partition(length(hilbert))) -> AbelianBases
Sector(
    quantumnumber::Abelian, hilbert::Hilbert{<:Spin}, partition::Tuple{Vararg{AbstractVector{Int}}}=partition(length(hilbert));
    table::AbstractDict=Table(hilbert, Metric(EDKind(hilbert), hilbert))
) -> AbelianBases

Construct the Abelian bases of a spin Hilbert space with the specified quantum number.

Sector

A sector of the Hilbert space which forms the bases of an irreducible representation of the Hamiltonian of a quantum lattice system.

Sector(hilbert::Hilbert{<:Fock}, basistype::Type{<:Unsigned}=UInt) -> BinaryBases
Sector(quantumnumber::ℕ, hilbert::Hilbert{<:Fock}, basistype::Type{<:Unsigned}=UInt; table::AbstractDict=Table(hilbert, Metric(EDKind(hilbert), hilbert))) -> BinaryBases
Sector(quantumnumber::Union{𝕊ᶻ, Abelian[ℕ ⊠ 𝕊ᶻ], Abelian[𝕊ᶻ ⊠ ℕ]}, hilbert::Hilbert{<:Fock}, basistype::Type{<:Unsigned}=UInt; table::AbstractDict=Table(hilbert, Metric(EDKind(hilbert), hilbert))) -> BinaryBases

Construct the binary bases of a Hilbert space with the specified quantum number.

SectorFilter{S} <: LinearTransformation

Filter the target bra and ket Hilbert spaces.

SimpleAbelianQuantumNumber <: AbelianQuantumNumber

Abstract type of simple Abelian quantum numbers. That is, it contains only one label.

(state::SpinCoherentState)(bases::AbelianBases, table::AbstractDict, dtype=ComplexF64) -> Vector{dtype}

Get the vector representation of a spin coherent state with the given Abelian bases and table.

SpinCoherentState <: CompositeDict{Int, Tuple{Float64, Float64}}

Spin coherent state on a block of lattice sites.

The structure of the spin coherent state is specified by a Dict{Int, Tuple{Float64, Float64}}, which contains the site-(θ, ϕ) pairs with site being the site index in a lattice and (θ, ϕ) denoting the polar and azimuth angles in radians of the classical magnetic moment on this site.

SpinCoherentState(structure::AbstractDict{Int, <:AbstractVector{<:Number}})
SpinCoherentState(structure::AbstractDict{Int, <:NTuple{2, Number}}; unit::Symbol=:radian)

Construct a spin coherent state on a block of lattice sites.

SpinCoherentStateProjection <: Action

Projection of states obtained by exact diagonalization method onto spin coherent states.

SpinCoherentStateProjection(configuration::SpinCoherentState, polars::AbstractVector{<:Real}, azimuths::AbstractVector{<:Real})
SpinCoherentStateProjection(configuration::SpinCoherentState, np::Integer, na::Integer)

Construct a SpinCoherentStateProjection.

SpinCoherentStateProjectionData <: Data

Data of spin coherent state projection, including:

1. polars::Vector{Float64}: global polar angles of the spin coherent states.
2. azimuths::Vector{Float64}: global azimuth angles of the spin coherent states.
3. values::Matrix{Float64}: projection of the state obtained by exact diagonalization method onto the spin coherent states.

StaticTwoPointCorrelator{O<:Union{Operator, Operators}, R<:ReciprocalSpace} <: Action

Static two-point correlation function.

StaticTwoPointCorrelatorData{R<:ReciprocalSpace, V<:Array{Float64}} <: Data

Data of static two-point correlation function, including:

1. reciprocalspace::R: reciprocal space to compute the static two-point correlation function.
2. values::V: values of the static two-point correlation function.

fℤ₂ <: ℤ{2}

Fermion parity.

sℤ₂ <: ℤ{2}

Spin parity.

ℕ <: <: 𝕌₁

Concrete Abelian quantum number of the particle number.

ℤ{N} <: SimpleAbelianQuantumNumber

Abstract type of ℤₙ quantum numbers.

ℤ₁ <: ℤ{1}

ℤ₁, i.e., the trivial quantum number.

𝕊ᶻ <: 𝕌₁

Concrete Abelian quantum number of the z-component of a spin.

𝕌₁ <: SimpleAbelianQuantumNumber

Abstract type of 𝕌₁ quantum numbers.

(index::CompositeIndex)(quantumnumber::Abelian) -> Abelian

Get the resulting Abelian quantum number after a CompositeIndex acts upon an initial Abelian quantum number.

(index::Index)(quantumnumber::Abelian) -> Abelian

Get the resulting Abelian quantum number after an Index acts upon an initial Abelian quantum number.

Metric(::EDKind{:Abelian}, ::Hilbert{<:Spin}) -> OperatorIndexToTuple

Get the index-to-tuple metric for a canonical quantum spin lattice system.

Metric(::EDKind{:Binary}, ::Hilbert{<:Fock}) -> OperatorIndexToTuple

Get the index-to-tuple metric for a canonical quantum Fock lattice system.

(op::OperatorProd)(quantumnumber::Abelian) -> Abelian

Get the resulting Abelian quantum number after an OperatorProd acts upon an initial Abelian quantum number.

(ops::OperatorSet)(quantumnumber::Abelian) -> Abelian

Get the resulting Abelian quantum number after an OperatorSet acts upon an initial Abelian quantum number.

(index::FockIndex)(quantumnumber::ℤ₁) -> ℤ₁
(index::FockIndex)(quantumnumber::ℕ) -> ℕ
(index::FockIndex)(quantumnumber::𝕊ᶻ) -> 𝕊ᶻ
(index::FockIndex)(quantumnumber::(ℕ ⊠ 𝕊ᶻ)) -> ℕ ⊠ 𝕊ᶻ
(index::FockIndex)(quantumnumber::(𝕊ᶻ ⊠ ℕ)) -> 𝕊ᶻ ⊠ ℕ

Get the resulting Abelian quantum number after a FockIndex acts upon an initial Abelian quantum number.

+(qn::AbelianQuantumNumber) -> typeof(qn)

Overloaded + operator for AbelianQuantumNumber.

+(qn₁::QN, qn₂::QN, qns::QN...) where {QN<:AbelianQuantumNumberProd} -> QN

Overloaded + operator for AbelianQuantumNumberProd.

+(qn₁::QN, qn₂::QN, qns::QN...) where {QN<:SimpleAbelianQuantumNumber} -> QN

Overloaded + operator for SimpleAbelianQuantumNumber.

-(qn::AbelianQuantumNumberProd) -> typeof(qn)
-(qn₁::QN, qn₂::QN) where {QN<:AbelianQuantumNumberProd} -> QN

Overloaded - operator for AbelianQuantumNumberProd.

-(qn::SimpleAbelianQuantumNumber) -> typeof(qn)
-(qn₁::QN, qn₂::QN) where {QN<:SimpleAbelianQuantumNumber} -> QN

Overloaded - operator for SimpleAbelianQuantumNumber.

broadcast(::Type{Sector}, quantumnumbers::OneAtLeast{Abelian}, hilbert::Hilbert, args...; table::AbstractDict=Table(hilbert, Metric(EDKind(hilbert), hilbert))) -> NTuple{fieldcount(typeof(quantumnumbers)), Sector}

Construct a set of sectors based on the quantum numbers and a Hilbert space.

broadcast(
    ::Type{Sector}, quantumnumbers::OneAtLeast{Abelian}, hilbert::Hilbert{<:Spin}, partition::NTuple{N, AbstractVector{Int}}=partition(length(hilbert));
    table::AbstractDict=Table(hilbert, Metric(EDKind(hilbert), hilbert))
) where N -> NTuple{fieldcount(typeof(quantumnumbers)), AbelianBases}

Construct a set of Abelian based based on the quantum numbers and a Hilbert space.

adjoint(gs::AbelianGradedSpace) -> typeof(gs)

Get the dual of an Abelian graded space.

count(basis::BinaryBasis) -> Int
count(basis::BinaryBasis, start::Integer, stop::Integer) -> Int

Count the number of occupied single-particle states for a binary basis.

count(data::EDEigenData) -> Int

Count the number of eigen value-vector-sector groups contained in an EDEigenData.

cumsum(rs::RepresentationSpace, i::Union{Integer, CartesianIndex}) -> Int

Get the accumulative degenerate dimension up to the ith Abelian quantum number contained in a representation space.

cumsum(gs::AbelianGradedSpace{QN}, qn::QN) where {QN<:AbelianQuantumNumber} -> Int

Get the accumulative dimension of an Abelian graded space up to a certain Abelian quantum number contained in an Abelian graded space.

eltype(gf::AbstractGreenFunction)
eltype(::Type{<:AbstractGreenFunction{T}}) where {T<:Number}

Get the eltype of an AbstractGreenFunction.

getindex(gs::AbelianGradedSpace, indexes::AbstractVector{<:Integer}) -> typeof(gs)
getindex(gs::AbelianGradedSpace{QN}, quantumnumbers::AbstractVector{QN}) where {QN<:AbelianQuantumNumber} -> AbelianGradedSpace{QN}

Get a subset of an Abelian graded space.

getindex(gs::AbelianGradedSpace, i::Union{Integer, CartesianIndex})

Get the ith Abelian quantum number contained in an Abelian graded space.

getindex(qn::AbelianQuantumNumberProd, i::Integer) -> SimpleAbelianQuantumNumber

Get the ith simple Abelian quantum number in a Deligne tensor product.

getindex(::Type{Abelian}, ::Type{T}) where {T<:AbelianQuantumNumber} -> Type{T}

Overloaded [] for Abelian, i.e., the support of syntax Abelian[T] where T<:AbelianQuantumNumber, which is helpful for the construction of tensor producted Abelian quantum numbers.

in(qn::QN, gs::AbelianGradedSpace{QN}) where {QN<:AbelianQuantumNumber} -> Bool

Check whether an Abelian quantum number is contained in an Abelian graded space.

inv(qn::AbelianQuantumNumber, bool::Bool=true) -> typeof(qn)

Get the inverse of an Abelian quantum number qn if bool is true. Otherwise, return qn itself.

isone(basis::BinaryBasis, state::Integer) -> Bool

Judge whether the specified single-particle state is occupied for a binary basis.

iszero(basis::BinaryBasis, state::Integer) -> Bool

Judge whether the specified single-particle state is unoccupied for a binary basis.

iterate(basis::BinaryBasis)
iterate(basis::BinaryBasis, state)

Iterate over the numbers of the occupied single-particle states.

length(gs::AbelianGradedSpace) -> Int

Get the number of inequivalent irreducible representations (i.e., the Abelian quantum numbers) of an Abelian graded space.

length(qn::AbelianQuantumNumberProd) -> Int

Get the length of a Deligne tensor product.

match(sector₁::Sector, sector₂::Sector) -> Bool

Judge whether two sectors match each other, that is, whether they can be used together as the bra and ket spaces.

merge(rs::AbelianGradedSpaceProd) -> Tuple{AbelianGradedSpace{eltype(rs)}, Dict{eltype(rs), Vector{NTuple{rank(rs), eltype(rs)}}}}

Get the decomposition of the direct product of several Abelian graded spaces and its corresponding fusion processes.

For a set of Abelian graded spaces (gs₁, gs₂, ...), their direct product space can contain several equivalent irreducible representations because for different sets of Abelian quantum numbers (qn₁, qn₂, ...) where qnᵢ∈gsᵢ, the fusion, i.e., ⊗(qn₁, qn₂, ...) may give the same result qn. This function returns the decomposition of the direct product of (gs₁, gs₂, ...) as well as all the fusion processes of each quantum number contained in the decomposition.

one(basis::BinaryBasis, state::Integer) -> BinaryBasis

Get a new binary basis with the specified single-particle state occupied.

pairs(rs::RepresentationSpace, ::typeof(dimension)) -> RepresentationSpacePairs
pairs(rs::RepresentationSpace, ::typeof(range)) -> RepresentationSpacePairs

Return an iterator that iterates over the pairs of the Abelian quantum numbers and their corresponding (slices of the) degenerate dimensions contained in a representation space.

range(bs::AbelianBases) -> AbstractVector{Int}

Get the range of the target sector of an AbelianBases in the direct producted bases.

range(gs::AbelianGradedSpace, qn::Union{Integer, CartesianIndex}) -> UnitRange{Int}
range(gs::AbelianGradedSpace{QN}, qn::QN) where {QN<:AbelianQuantumNumber} -> UnitRange{Int}

Get the slice of the degenerate dimension of an Abelian quantum number contained in an Abelian graded space.

range(rs::AbelianGradedSpaceProd, i::Union{Integer, CartesianIndex}) -> AbstractVector{Int}

Get the slice of the degenerate dimension of the ith Abelian quantum number in the direct product of several Abelian graded spaces.

range(rs::AbelianGradedSpaceSum, i::Union{Integer, CartesianIndex}) -> UnitRange{Int}

Get the slice of the degenerate dimension of the ith Abelian quantum number in the direct sum of several Abelian graded spaces.

range(rs::AbelianGradedSpaceProd{N, QN}, qns::NTuple{N, QN}) where {N, QN<:AbelianQuantumNumber} -> AbstractVector{Int}

Get the slice of the degenerate dimension of the Abelian quantum number fused by qns in the direct product of several Abelian graded spaces.

size(gf::AbstractGreenFunction) -> NTuple{2, Int}

Get the size of an AbstractGreenFunction.

split(target::QN, rs::AbelianGradedSpaceProd{N, QN}; nmax::Real=20) where {N, QN<:AbelianQuantumNumber} -> Set{NTuple{N, QN}}

Find a set of splittings of the target Abelian quantum number with respect to the direct product of several Abelian graded spaces.

values(qn::AbelianQuantumNumberProd) -> NTuple{rank(qn), Number}

Get the values of the simple Abelian quantum numbers in a Deligne tensor product.

values(qn::SimpleAbelianQuantumNumber) -> Tuple{Number}

Get the value of a simple Abelian quantum number and return it as the sole element of a tuple.

zero(qn::AbelianQuantumNumber) -> typeof(qn)
zero(::Type{QN}) where {QN<:AbelianQuantumNumber} -> QN

Get the zero Abelian quantum number.

zero(basis::BinaryBasis, state::Integer) -> BinaryBasis

Get a new binary basis with the specified single-particle state unoccupied.

⊠(bs::BinaryBases, another::Abelian) -> BinaryBases
⊠(another::Abelian, bs::BinaryBases) -> BinaryBases

Deligne tensor product the quantum number of a set of binary bases with another quantum number.

⊠(qn::SimpleAbelianQuantumNumber, qns::SimpleAbelianQuantumNumber...) -> AbelianQuantumNumberProd
⊠(qn₁::SimpleAbelianQuantumNumber, qn₂::AbelianQuantumNumberProd) -> AbelianQuantumNumberProd
⊠(qn₁::AbelianQuantumNumberProd, qn₂::SimpleAbelianQuantumNumber) -> AbelianQuantumNumberProd
⊠(qn₁::AbelianQuantumNumberProd, qn₂::AbelianQuantumNumberProd) -> AbelianQuantumNumberProd

Deligne tensor product of Abelian quantum numbers.

⊠(QN::Type{<:SimpleAbelianQuantumNumber}, QNS::Type{<:SimpleAbelianQuantumNumber}...) -> Type{AbelianQuantumNumberProd{Tuple{QN, QNS...}}}
⊠(::Type{QN}, ::Type{AbelianQuantumNumberProd{T}}) where {QN<:SimpleAbelianQuantumNumber, T<:Tuple{Vararg{SimpleAbelianQuantumNumber}}} -> Type{AbelianQuantumNumberProd{Tuple{QN, fieldtypes(T)...}}}
⊠(::Type{AbelianQuantumNumberProd{T}}, ::Type{QN}) where {T<:Tuple{Vararg{SimpleAbelianQuantumNumber}}, QN<:SimpleAbelianQuantumNumber} -> Type{AbelianQuantumNumberProd{Tuple{fieldtypes(T)...}, QN}}
⊠(::Type{AbelianQuantumNumberProd{T₁}}, ::Type{AbelianQuantumNumberProd{T₂}}) where {T₁<:Tuple{Vararg{SimpleAbelianQuantumNumber}}, T₂<:Tuple{Vararg{SimpleAbelianQuantumNumber}}} -> Type{AbelianQuantumNumberProd{Tuple{fieldtypes(T₁)..., fieldtypes(T₂)...}}}

Deligne tensor product of Abelian quantum numbers.

basistype(i::Integer)
basistype(::Type{I}) where {I<:Integer}

Get the binary basis type corresponding to an integer or a type of an integer.

findindex(position::Integer, gs::AbelianGradedSpace, guess::Integer) -> Int

Find the index of an Abelian quantum number in an Abelian graded space beginning at guess whose position in the complete dimension range is position.

prepare!(ed::ED; timer::TimerOutput=edtimer) -> ED
prepare!(ed::Algorithm{<:ED}) -> Algorithm{<:ED}

Prepare the matrix representation.

productable(sector₁::Sector, sector₂::Sector) -> Bool

Judge whether two sectors could be direct producted.

regularize!(quantumnumbers::Vector{<:AbelianQuantumNumber}, dimensions::Vector{Int}; check::Bool=false) -> Tuple{typeof(quantumnumbers), typeof(dimensions), Vector{Int}}

In place regularization of the input Abelian quantum numbers and their corresponding degenerate dimensions.

After the regularization, the Abelian quantum numbers will be sorted in the ascending order and duplicates will be merged together. The degenerate dimensions will be processed accordingly. When check is true, this function also check whether all input degenerate dimensions are positive. The regularized Abelian quantum numbers and degenerate dimensions, as well as the permutation vector that sorts the input Abelian quantum numbers, will be returned.

regularize(quantumnumbers::AbstractVector{<:AbelianQuantumNumber}, dimension::AbstractVector{<:Integer}; check::Bool=false) -> Tuple{Vector{eltype(quantumnumbers)}, Vector{Int}, Vector{Int}}

Regularize of the input Abelian quantum numbers and their corresponding degenerate dimensions.

See regularize!.

release!(ed::ED; gc::Bool=true) -> ED
release!(ed::Algorithm{<:ED}; gc::Bool=true) -> Algorithm{<:ED}

Release the memory source used in preparing the matrix representation. If gc is true, call the garbage collection immediately.

sumable(sector₁::Sector, sector₂::Sector) -> Bool

Judge whether two sectors could be direct summed.

eigen(ed::ED, sectors::Union{Abelian, Sector}...; timer::TimerOutput=edtimer, release::Bool=false, kwargs...) -> EDEigenData
eigen(ed::Algorithm{<:ED}, sectors::Union{Abelian, Sector}...; release::Bool=false, kwargs...) -> EDEigenData

Solve the eigen problem by the restarted Lanczos method provided by the Arpack package.

eigen(m::EDMatrix; nev::Int=1, which::Symbol=:SR, tol::Real=1e-12, maxiter::Int=300, v₀::Union{AbstractVector{<:Number}, Int}=dimension(m.bra), krylovdim::Int=max(20, 2*nev+1), verbosity::Int=0) -> EDEigenData

Solve the eigen problem by the restarted Lanczos method provided by the KrylovKit package.

eigen(
    ms::OperatorSum{<:EDMatrix};
    nev::Int=1,
    which::Symbol=:SR,
    tol::Real=1e-12,
    maxiter::Int=300,
    v₀::Union{Dict{<:Abelian, <:Union{AbstractVector{<:Number}, Int}}, Dict{<:Sector, <:Union{AbstractVector{<:Number}, Int}}}=Dict(Abelian(m.ket)=>dimension(m.ket) for m in ms),
    krylovdim::Int=max(20, 2*nev+1),
    verbosity::Int=0,
    timer::TimerOutput=edtimer
) -> EDEigenData

Solve the eigen problem by the restarted Lanczos method provided by the Arpack package.

rank(qn::AbelianQuantumNumberProd) -> Int
rank(::Type{<:AbelianQuantumNumberProd}) -> Int

Get the rank of a Deligne tensor product of simple Abelian quantum numbers.

rank(rs::CompositeAbelianGradedSpace) -> Int
rank(::Type{<:CompositeAbelianGradedSpace{N}}) where N -> Int

Get the number of Abelian graded spaces in the direct sum.

rank(gf::GreenFunction) -> Int

Get the rank of a GreenFunction.

rank(gf::RetardedGreenFunction) -> Int

Get the rank of a RetardedGreenFunction.

⊕(gs::AbelianGradedSpace, gses::AbelianGradedSpace...) -> AbelianGradedSpaceSum
⊕(gs::AbelianGradedSpace, rs::AbelianGradedSpaceSum) -> AbelianGradedSpaceSum
⊕(rs::AbelianGradedSpaceSum, gs::AbelianGradedSpace) -> AbelianGradedSpaceSum
⊕(rs₁::AbelianGradedSpaceSum, rs₂::AbelianGradedSpaceSum) -> AbelianGradedSpaceSum

Get the direct sum of some Abelian graded spaces.

⊗(gs::AbelianGradedSpace, gses::AbelianGradedSpace...) -> AbelianGradedSpaceProd
⊗(gs::AbelianGradedSpace, rs::AbelianGradedSpaceProd) -> AbelianGradedSpaceProd
⊗(rs::AbelianGradedSpaceProd, gs::AbelianGradedSpace) -> AbelianGradedSpaceProd
⊗(rs₁::AbelianGradedSpaceProd, rs₂::AbelianGradedSpaceProd) -> AbelianGradedSpaceProd

Get the direct product of some Abelian graded spaces.

⊗(qn::AbelianQuantumNumber, qns::AbelianQuantumNumber...) -> eltype(qns)

Get the direct product of some AbelianQuantumNumbers.

⊗(bs₁::BinaryBases, bs₂::BinaryBases) -> BinaryBases

Get the direct product of two sets of binary bases.

⊗(basis₁::BinaryBasis, basis₂::BinaryBasis) -> BinaryBasis

Get the direct product of two binary bases.

partition(n::Int) -> NTuple{2, Vector{Int}}

Get the default partition of n local Hilbert spaces.

matrix(ops::Operators, braket::NTuple{2, Sector}, table::AbstractDict, dtype=scalartype(ops)) -> SparseMatrixCSC{dtype, Int}

Get the CSC-formed sparse matrix representation of a set of operators.

Here, table specifies the order of the operator indexes.

matrix(index::OperatorIndex, graded::Graded, dtype::Type{<:Number}=ComplexF64) -> Matrix{dtype}

Get the matrix representation of an OperatorIndex on an Abelian graded space.

matrix(index::SpinIndex, graded::Graded, dtype::Type{<:Number}=ComplexF64) -> Matrix{dtype}

Get the matrix representation of a SpinIndex on an Abelian graded space.

matrix(ed::ED, sectors::Union{Abelian, Sector}...; timer::TimerOutput=edtimer, release::Bool=false) -> OperatorSum{<:EDMatrix}
matrix(ed::Algorithm{<:ED}, sectors::Union{Abelian, Sector}...; release::Bool=false) -> OperatorSum{<:EDMatrix}

Get the sparse matrix representation of a quantum lattice system in the target space.

matrix(op::Operator{V, <:OneAtLeast{OperatorIndex}}, braket::NTuple{2, AbelianBases}, table::AbstractDict, dtype=V) where V -> SparseMatrixCSC{dtype, Int}

Get the CSC-formed sparse matrix representation of an operator.

Here, table specifies the order of the operator indexes.

matrix(op::Operator{V, <:OneAtLeast{OperatorIndex}}, braket::NTuple{2, BinaryBases}, table::AbstractDict, dtype=V) where V -> SparseMatrixCSC{dtype, Int}

Get the CSC-formed sparse matrix representation of an operator.

Here, table specifies the order of the operator indexes.

matrix(op::Operator{V, Tuple{}}, braket::NTuple{2, Sector}, table::AbstractDict, dtype=V) where V -> SparseMatrixCSC{V, Int}

Get the CSC-formed sparse matrix representation of a scalar operator.

period(qn::AbelianQuantumNumberProd, i::Integer) -> Number
period(::Type{AbelianQuantumNumberProd{T}}, i::Integer) where {T<:Tuple{Vararg{SimpleAbelianQuantumNumber}}} -> Number

Get the period of the ith simple Abelian number contained in a Deligne tensor product.

period(qn::SimpleAbelianQuantumNumber) -> Number
period(::Type{QN}) where {QN<:SimpleAbelianQuantumNumber} -> Number

Get the period of a simple Abelian quantum number.

periods(qn::AbelianQuantumNumber) -> Tuple{Vararg{Number}}
periods(::Type{QN}) where {QN<:AbelianQuantumNumber} -> Tuple{Vararg{Number}}

Get the periods of Abelian quantum numbers.

decompose(rs::CompositeAbelianGradedSpace; expand::Bool=true) -> Tuple{AbelianGradedSpace{eltype(rs)}, Vector{Int}}

Decompose a composite of several Abelian graded spaces to the canonical one.

When expand is false, the corresponding permutation vector that sorts the Abelian quantum numbers will be returned as well. When expand is true, the expanded dimension indexes of the permutation vector that sorts the Abelian quantum numbers will be returned as well.

dimension(gs::AbelianGradedSpace, qn::Union{Integer, CartesianIndex}) -> Int
dimension(gs::AbelianGradedSpace{QN}, qn::QN) where {QN<:AbelianQuantumNumber} -> Int

Get the degenerate dimension of an Abelian quantum number contained in an Abelian graded space.

dimension(rs::AbelianGradedSpaceProd, i::Union{Integer, CartesianIndex}) -> Int

Get the degenerate dimension of the ith Abelian quantum number in the direct product of several Abelian graded spaces.

dimension(rs::AbelianGradedSpaceProd) -> Int

Get the total dimension of the direct product of several Abelian graded spaces.

dimension(rs::AbelianGradedSpaceSum, i::Union{Integer, CartesianIndex}) -> Int

Get the degenerate dimension of the ith Abelian quantum number in the direct sum of several Abelian graded spaces.

dimension(rs::AbelianGradedSpaceSum) -> Int

Get the total dimension of the direct sum of several Abelian graded spaces.

dimension(gs::AbelianGradedSpace) -> Int

Get the total dimension of an Abelian graded space.

dimension(gf::GreenFunction) -> Int

Get the dimension of the Krylov space expanded to obtained a GreenFunction.

dimension(rs::AbelianGradedSpaceProd{N, QN}, qns::NTuple{N, QN}) where {N, QN<:AbelianQuantumNumber} -> Int

Get the degenerate dimension of the Abelian quantum number fused by qns in the direct product of several Abelian graded spaces.

reset!(
    gf::GreenFunction, H::AbstractMatrix{<:Number}, V::AbstractVector{AbstractVector{<:Number}}, E₀::Real;
    ranks::AbstractVector{<:Integer}=1:rank(gf), dimensions::AbstractVector{<:Integer}=1:dimension(gf)
) -> typeof(gf)

Reset (a block) of GreenFunction.

value(qn::AbelianQuantumNumberProd, i::Integer) -> Number

Get the value of the ith simple Abelian quantum number in a Deligne tensor product.

value(qn::SimpleAbelianQuantumNumber) -> Number

Get the value of a simple Abelian quantum number.