Few-body reference data for multicomponent formalisms: Light-nuclei molecules

We present full quantum statistical energetics of some electron-light- nuclei systems. This is accomplished with the path-integral Monte Carlo method. The effects on energetics arising from the change in the nuclear mass are studied. The obtained results may serve as reference data for the multicomponent density functional theory calculations of light-nuclei systems. In addition, the results reported here will enable better fitting of today's electron-nuclear energy functionals, for which the description of light nuclei is most challenging in particular.