that the ANN method is useful to make predictions at ultra-large basis spaces using available data from NCSM calculations at smaller basis spaces. More discussions on these two methods are presented in each subsection.

Ab initio NCSM Method {#sec:NCSM}
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In the NCSM method, the neutrons and protons (separate species of nucleons) interact independently with each other. The Hamiltonian of $A$ nucleons contains kinetic energy ($T_{\rm rel}$) and interaction ($V$) terms $$\label{eq:Hamiltonian}
\begin{split}
    & H_A = T_{\rm rel} + V \\ 
    & = \frac{1}{A} \sum_{i<j} \frac{(\vec{p}_i - \vec{p}_j)^2}{2m} + \sum_{i<j}^{A}V_{ij} + \sum_{i<j<k}^{A}V_{ijk} + ~ \ldots,
\end{split}$$ where $m$ is the nucleon mass, $\vec{p}_i$ is the momentum of the $i$-th nucleon, $V_{ij}$ is the NN interaction including the Coulomb interaction between protons and $V_{ijk}$ is the NNN interaction. Higher-body interactions are also allowed and signified by the three dots. The HO center-of-mass (CM) Hamiltonian with a Lagrange multiplier is added to the Hamiltonian above to force the many-body eigenstates to factorize into a CM component times an intrinsic component as in [@SpuriousCMMotion:1974]. This way, the spurious CM excited states are pushed up above the physically relevant states, which have the lowest eigenstate of the HO for CM motion.

With the nuclear 