Fig. 2: Orbital rationalization of molecular reactivity.
a Orbital analysis of the reaction between ammonia and methyl chloride. Our discussion focuses on the analysis of the only occupied orbital having bonding character on both reagents, the HOMO-5 orbital. We notice that as the coupling increases the bond between carbon and nitrogen becomes weaker. In particular, for coupling λ = 0.2 the HOMO-5 is a simple composition of the non-bonding ammonia lone pair and the C-Cl sigma bond. This is verified using a projection of HOMO-5 on the orbitals of the fragments. The contributions are given in percentages. b, c Difference between electron densities computed at coupling λ = 0.1/0.2 and λ = 0.0. The blue regions of the isosurfaces show charge accumulation inside the cavity while the orange regions show charge depletion. In dark blue we plot the integral of the density differences to further display cavity induced charge reorganization26,33. The polarization of the field is placed along the C–Cl bond and the cavity frequency is 13.6 eV.
