  Harmonic oscillator model-space truncations introduce systematic errors to
the calculation of binding energies and other observables. We identify the
relevant infrared scaling variable and give values for this nucleus-dependent
quantity. We consider isotopes of oxygen computed with the coupled-cluster
method from chiral nucleon-nucleon interactions at next-to-next-to-leading
order and show that the infrared component of the error is sufficiently
understood to permit controlled extrapolations. By employing oscillator spaces
with relatively large frequencies, well above the energy minimum, the
ultraviolet corrections can be suppressed while infrared extrapolations over
tens of MeVs are accurate for ground-state energies. However, robust
uncertainty quantification for extrapolated quantities that fully accounts for
systematic errors is not yet developed.
