Figure 2.

First four light–matter correlated eigenvalues with (blue, solid) and without (blue, dashed) the self-polarization contribution ¹/₂(λ·R)² as well as the total dipole moment R = −x + ZX with (red, solid) and without (red, dashed) self-polarization. While observables start to be converged with a box size around 50 Å, without self-polarization the system starts to disintegrate already for slightly larger box sizes, as highlighted by the inset.