PNNL

Abstract

We extend the Many Body Expansion (MBE), previously applied to hydrogen bonded and molecular systems, to the light nuclear systems 3H and 3He by considering the protons and neutrons as the “bodies” in the expansion. The analysis is based on the Pauli Nucleonic Dynamics (PND) model, an anti-symmetrized version of the Constrained Molecular Dynamics (CoMD) model. The total energy of the 2H nucleus is calculated with this model at -2.312 MeV, which is within 4% of the experimental value of -2.225 MeV. The application of the MBE yields results for the 3-body term in the 3H nucleus that are comparable with previous estimates, while it is reported for the first time for the nucleus of 3He. The energies of 3H and 3He that include the sum of the 1- and 2-body terms with the model are - 6.876 MeV and -6.088 eV and the 3-body terms, estimated from the difference of the sum of the 1- and 2-body terms from the experimentally measured energies, are -1.606 MeV and -1.630 MeV, respectively. The MBE for the 3H and 3He nuclei is qualitatively similar to the one previously reported for the water trimer: the 2- and 3-body terms are negative with the latter amounting to ~3% of the former. Additionally, the 3-body terms correspond to about 20 % of the total energy of the bound systems, a percentage that is also comparable to the one in the water trimer (17%). In this manner, the MBE analysis can be applied to light nuclear systems following the same protocol as the one that has been previously extensively used for hydrogen bonded molecular systems.