Search for an equation of motion of a classical pointlike charge
  In 1892 H.A. Lorentz started the search for a classical equation of motion for pointlike charged particles that takes into account the radiation reaction force. This search culminated in the Lorentz-Abraham-Dirac equation of motion, which is not satisfactory since it exhibits self-acceleration causing runaway solutions. In spite of ongoing efforts for more than a century, there is yet no acceptable classical equation of motion for a pointlike charge, cf. the recent paper by Rohrlich and the comments about his proposal. So, it is still an open question how to augment continuous classical electrodynamics with the physical concept of pointlike charged particles. The pointlike charge is presently only a common and handy computational device, which we generalized by the expansions in terms of co-moving moments of time-dependent, moving charges and currents. 
Marijan Ribaric and Luka Sustersic