The role of ionic structures in the response of a non-polar molecule to an electric field

Going beyond one- and two- electron distributions, we investigate the behavior of ionic structures of chemical bonds, and the role that play in the response of a non-polar molecule to an electric field. We use as model non-polar molecule the cis-butadiene, and we examine the behavior of its ionic structures with respect to a longitudinal and a perpendicular electric field direction. The probabilities (weights) of various types of ionic structures are estimated by means of poly-electron population analysis in the basis of natural atomic orbitals, and their behavior is explained and rationalized by means of a Field Component Analysis. The electric field polarizes the bond dipoles according to its direction, and in this framework, the relative orientations of these local dipoles, which can be favorable or unfavorable to the chemical bonding, control the overall response of the molecular system to the external stimulus.