Quantum-Mechanical Treatment of Helium Hydride Molecule-Ion HeH+

Helium hydride molecule-ion has been treated by the variation method, including ionic and polarization terms in the variation function and varying the effective nuclear charge. The equilibrium internuclear distance is found to be 1.57a0. Fitting a parabola to the lower part of the best potential energy curve leads to a value of 0.43 megadyne/cm for the force constant and a value of 2800 cm—1 for the fundamental vibration frequency. The minimum energy obtained for the system is —5.844WH, which, when subtracted from the best value for the energy of the helium atom using the same type of variation function, gives a value for the dissociation energy of 2.02 ev. The doubly charged ion, HeH++, is found to be unstable.