We combine a recently developed ab initio many-body approach capable of describing simultaneously both bound and scattering states, the ab initio no-core shell model/resonating-group method (NCSM/RGM), with an importance-truncation scheme for the cluster eigenstate basis and demonstrate its applicability to nuclei with mass numbers as high as 17. By using soft similarity renormalization-group-evolved chiral nucleon-nucleon interactions, we first calculate nucleon-${}^4\mathrm{He}$ phase shifts, cross sections, and analyzing powers. Next, we investigate nucleon scattering on ${}^7\mathrm{Li}$, ${}^7\mathrm{Be}$, ${}^{12}\mathrm{C}$, and ${}^{16}\mathrm{O}$ in coupled-channel NCSM/RGM calculations that include low-lying excited states of these nuclei. We check the convergence of phase shifts with the basis size and study $A=8,13$, and 17 bound and unbound states. Our calculations predict low-lying resonances in ${}^8\mathrm{Li}$ and ${}^8\mathrm{B}$ that have not been experimentally clearly identified yet. We are able to reproduce reasonably well the structure of the $A=13$ low-lying states. However, we find that $A=17$ states cannot be described without an improved treatment of ${}^{16}\mathrm{O}$ one-particle-one-hole excitations and $\alpha$ clustering.

• Received 26 July 2010

DOI:https://doi.org/10.1103/PhysRevC.82.034609