To further understand the role of the optical cavity in inducing these chemical changes, we compute the ground state electron density difference between molecules placed inside the cavity and outside the cavity. This comparison allows a direct visualization of the cavity-mediated changes to the electron density and facilitates chemical insights into the relative stability of the various substituted reaction intermediates. The difference density function of the ground state is defined as ∆ρ(X, Y, Z) = ρ M 00 (X, Y, Z) -ξ 00 (X, Y, Z), where ρ M 00 is the polaritonic ground state electronic density (with the photonic degrees of freedom integrated out) and ξ 00 is the bare electronic ground state density. Theoretical details for computing ρ M 00 (X, Y, Z) and ξ 00 (X, Y, Z) are provided in the Supporting Information. Further, a discussion regarding the contributions to the polaritonic ground state density matrix with respect to the calculated the electronic densities can be found in the Supporting Information. To help visualize the density difference, we further integrate out the Z-direction (perpendicular to the plane of the benzene ring) and present the two-dimensional density differences, ∆ρ(X, Y ) = dZ∆ρ(X, Y, Z). Fig. shows the electron density difference when the cavity polarization is along ê = (θ 1 , ϕ 1 ) (see Fig. and inset to Fig. for the polarization direction projected onto the XY-plane). The rest of the parameters are the same as in Fig. , with A 0 = 0.3 a.u. and ω c = 1.8 eV. Under these conditions, the ortho-substituted Wheland intermediate becomes more stable than the metasubstituted intermediate (see Fig. ) by ∼ 6.4 kcal/mol. Fig. shows the density difference for the meta-substituted reaction intermediate while Fig. presents the density difference for the ortho-substituted reaction intermediate. The color scheme of this plot is: red (positive values) indicates the accumulation of electron density and blue (negative values) indicates depletion of electron density upon coupling of the molecule into the cavity. Fig. in the Supporting Information shows data for the meta (Fig. ) and parasubstituted (Fig. ) intermediate species.