The strong and weak nuclear forces are insanely hard to simulate directly. You might have a look at e.g. this paper for some fairly current modelling: https://journals.aps.org/prc/abstract/10.1103/PhysRevC.103.0...

Just to be clear, simulating the atomic nucleus isotope stability (like here) is something entirely completely different than simulating the quantum mechanics of electrons in one or more atoms (like we do in DFT), or simulating molecules (like we do e.g. in molecular dynamics). The latter two are comparably much easier.