Ab initio isotope simulated dynamics in the adiabatic approximation

We present, for the first time, ab initio simulated molecular dynamics within the adiabatic approximation. The tests are made for H2+ and its isotopomers. We show that the forces on the nuclei can be calculated with sufficient accuracy to distinguish among the isotopomers. We also show that there are two regions where these forces are non-negligible, compared to those of Born–Oppenheimer: at large nuclear distances and near the equilibrium positions.