Charge migration in HCCI + has been studied extensively, both experimentally and computationally. Strong field ionization of HCCI produces a coherent superposition of the X and A states of HCCI + . This results in charge migration between the CC triple bond and the iodine with a period of 1.87 fs. The coherent superposition and charge migration decay in 15 -20 fs because the vibrational wavepackets on the X and A potential energy surfaces move in opposite directions. Charge migration has also been studied in a number of other systems, including some closely related molecules, HCCBr, H(CC)nBr and H(CC)nI cations, but not in HCCCl + and HCCF + .