Quantum effects of nuclear motion in three-particle diatomic ions

A high accuracy, non-relativistic wavefunction is used to study nuclear motion in the ground state of three-particle {a+1a+2a-3} electronic and muonic molecular systems without assuming the Born Oppenheimer approximation. Intracule densities and center of mass particle densities show that as the mass ratio mai/ma3, i=1,2, becomes smaller, the localisation of the like-charged particles (nuclei) a1 and a2 decreases. A new coordinate system is used to calculate center of mass particle densities for systems where a1?a2. It is shown that the nuclear motion is strongly correlated and depends on the relative masses of the nuclei a1 and a2 rather than just their absolute mass. The heavier particle is always more localised and, the lighter the partner mass, the greater the localisation. It is shown, for systems with ma1