Spin Migration in the Argon Dimer

We introduce the concept of \emph{spin migration}, i.e. time-dependent spin density, and the absolute smallest example of molecular spintronics. We illustrate the concept by \emph{ab initio} calculations of the coupled vibronic motion of the electrons and the nuclei in the argon dimer cation, in which the vibrational level spacing is similar to the spin–orbit splitting of the atomic argon cations. We find that the spin density varies on multiple time scales, given by the natural time scales of the electronic and nuclear wavepackets.