Systematic expansion for infrared oscillator basis extrapolations

Understand

Recent work has demonstrated that the infrared effects of harmonic oscillator basis truncations are well approximated by imposing a partial-wave Dirichlet boundary condition at a properly identified radius L.

• This led to formulas for extrapolating the corresponding energy E_L and other observables to infinite L and thus infinite basis size.
• Here we reconsider the energy for a two-body system with a Dirichlet boundary condition at L to identify and test a consistent and systematic expansion for E_L that depends only on observables.
• We also generalize the energy extrapolation formula to nonzero angular momentum, and apply it to the deuteron.