Quantum fluid density functional theory of chemical reactivity in a two-state ensemble

Abstract

A quantum fluid density functional approach is adopted in monitoring the dynamics of various global and local reactivity parameters of a helium atom in a two-state equiensemble, having an interaction with an external laser field as well as an incoming proton. The effect of an increase in the excited-state contribution in a two-state ensemble is more pronounced in global reactivity parameters than the local ones. Global reactivity indices are found to be more sensitive to the external perturbation, for the whole time-dependent process, than the local indices. Most of the local quantities show drastic changes only at the beginning of the processes. In the atom–field interaction problem, electronegativity, polarizability and entropy oscillate with the field and hardness attains a steady value after the initial transients die out. The ion–atom collision process can be divided into three distinct regimes in terms of the time-dependent electronegativity profile. In the encounter regime, hardness and entropy maximize and polarizability minimizes. Dynamical variants of the principles of maximum hardness, maximum entropy and minimum polarizability are shown to be operative.