Figure 3.

The two-dimensional Singlet HeH${}^{+}$ + He PES in eV for the motion of the helium atom (purple square) around the fixed positions of the hydrogen and other helium atom (gray and purple circles, respectively) in the ${}^1{\mathsf{\Sigma }}_g^{+}$ HeHHe${}^{+}$ molecule. The minimum corresponds to the geometry of the ${}^1{\mathsf{\Sigma }}_g^{+}$ state.