Ab initio molecular treatment of charge-transfer processes induced by collision of carbon ions with 5-halouracil molecules

The charge transfer in the collision of C4+ ions on 5-halouracil molecules has been studied theoretically by means of ab initio quantum chemistry molecular methods followed by a semiclassical dynamical treatment. The process appears markedly less efficient than the corresponding charge transfer with a uracil target which induces an enhancement of the complementary fragmentation process in agreement with the radio sensitivity of 5-halouracil molecules widely recognized. The mechanism seems to be driven by both electronic and steric effects which induce a lowering of the charge transfer cross sections and favor various orientations of the projectile with respect to the 5-halouracil target considered.