  We renormalize the chiral effective field theory (EFT) potential in
harmonic-oscillator (HO) model space. The low energy constants (LECs) are
utilized to absorb not just the ultra-violet part of the physics due to the
cutoff, but also the infrared part due to the truncation of model space. We use
the inverse J-matrix method to reproduce the nucleon-nucleon (NN) scattering
phase shifts in the given model space. We demonstrate that by including the NLO
correction, the nucleon-nucleon scattering in the continuum could be well
reproduced in the truncated HO trap space up to laboratory energy $T_{lab}=100$
MeV with number of HO basis $n_{max}$ as small as 10. A perturbative power
counting starts at subleading order is adopted in this work, and how to extract
the perturbative contribution is demonstrated. Our work serves as the input to
perform ab-initio calculations.
