Borromean binding in H-2 with Yukawa potential: A nonadiabatic quantum Monte Carlo study

The stability of the ground state of the H+2 and H2 systems, where nuclei and electrons interact through a Yukawa potential e-λr /r , has been studied for different values of the screening parameter λ using quantum Monte Carlo techniques. Nonadiabatic calculations using explicitly correlated trial wave functions were carried out, obtaining exact results within the statistical errors. H+2 and H2 appear to be stable species for values of λ as large as 1.35 and 1.38 bohr-1 . So in the range 1.35⩽λ⩽1.38 bohr-1 H2 is stable, while all the possible fragments are unbound, that is, it shows Borromean binding.