Function sequant::mbpt::decompositions::cumulant_to_density

• Defined in File rdm.cpp

Function Documentation

ExprPtr sequant::mbpt::decompositions::cumulant_to_density(ExprPtr ex_)

Returns:

the expansion of the cumulant κ_k ex_ (any k ≥ 1) in densities, κ_k = Σ_λ (-1)^(m-1) (m-1)! A[γ_λ₁ ⋯ γ_λₘ] over the integer partitions λ of k into m parts, where A[⋯] is the sum of the distinct antisymmetrized terms that mbpt::antisymmetrize generates, e.g. κ₃ = γ₃ - A[γ₂γ₁] + 2 A[γ₁γ₁γ₁]; the result is expanded, not simplified