Concerted quantum effects of electronic and nuclear fluxes in molecules

Common myth suggests synchronicity and unidirectionality of nuclear and electronic fluxes. Accurate quantum dynamics simulations of the vibrating model system, aligned H 2 + , confirm this rule, but with exceptional opposite behaviours during short periods in the attosecond time domain. The ratio of electronic versus nuclear fluxes increases systematically, from small to large amplitude nuclear motions. Visualization of the electronic and nuclear densities and flux densities reveals that this is due to broader dispersion of electronic wavepackets compared to nuclear ones. The accurate results validate an efficient general method for quantum calculations of the fluxes in terms of densities, not flux densities.