Three interacting atoms in a one-dimensional trap: a benchmark system for computational approaches

We provide an accurate calculation of the energy spectrum of three atoms interacting through a contact force in a one-dimensional harmonic trap, considering both spinful fermions and spinless bosons. We use fermionic energies as a benchmark for the exact-diagonalization technique (also known as full configuration interaction), which is found to slowly converge in the case of strong inter-atomic attraction.