Dynamics of electron correlation in simple systems

An overview of the dynamics of electron correlation is given for interactions of fast charged particles, ions and photons with simple atoms and molecules. For dynamic systems the emphasis is on evaluation of transition probabilities. In the uncorrelated limit the transition probability reduces to a product of independent single electron probabilities. The corresponds to the reduction of a correlated many electron wavefunction to a time dependent Hartree-Fock wavefunction. Special attention is given to collisions with mutiple electron transitions. In fast collisions multiple transitions are dominately caused by electron correlation. Double ionization of helium by high energy photons from synchrotrons is now well understood, but double ionization by fast electrons, positrons, protons and anti-protons is not yet so well understood