  In the present paper, we have calculated the energy spectra for neutron rich
$^{18-22}$N isotopes using no core shell model (NCSM).To calculate the energy
spectrum we have used three different $NN$ potentials, inside non-local outside
Yukawa (INOY), next-to-next-to-next-leading order (N3LO) from chiral effective
field theory and charge-dependent Bonn 2000 (CDB2K). The INOY potential, which
is a two body interaction but also have the effect of three body forces by
short range and non local character present in it. The calculations have been
done at $\hbar\Omega$=20 MeV, 14 MeV and 12 MeV using INOY, N3LO and CDB2K
potentials, respectively. Apart from this, we have also performed shell model
calculations with the YSOX interaction.The results with INOY interaction show
good agreement with the experimental data in comparison to other three
interactions. We have also shown the occupancy of different orbitals involved
corresponding to the largest model space ($N_{max}$= 4) in the present
calculations.
