Stark mixing under full interaction in ion-Rydberg atom cold collisions

A molecular dynamics simulation technique was developed to determine Stark mixing transitions, $n\ell\rightarrow n \ell'$, in Rydberg atoms. The full ion-Rydberg atom interaction could therefore be employed. The transition probabilities were compared with the previous exact analytical results which are appropriate only to the ion-dipole interaction. The effect of higher-order multipoles could therefore be assessed. It is shown that the full interaction becomes important at extremely low incident speeds $v$ and small-intermediate impact parameters $b$. This importance is illustrated via various contour plots in the $b,v$-plane.