Function sequant::mbpt::bernoulli::detail::R_part

Function Documentation

ExprPtr sequant::mbpt::bernoulli::detail::R_part(const ExprPtr &expr, std::size_t cutoff, std::size_t min_rank)

\(R\) part ( \(O_R\) of 10.1063/1.5030344: expr minus its \(N\) part). Unlike N_part the result is NOT block-resolved; it stays in compact general-index form, which is much cheaper for the nested commutators that consume \(R\).

Parameters:

  • expr – expression to partition

  • cutoff – highest excitation/de-excitation rank in \(O_N\)

  • min_rank – lowest rank \(\sigma\) carries