Figure 11.

Dissociation of the chromium dimer with different shifts and regularization techniques. The real shift removes all intruders only with a large ε value, however significantly shifting the potential energy curve. On the other hand, the two regularizers require a smaller regularization value. The inset shows the discontinuity of σ¹-CASPT2 around the equilibrium as compared to the smooth curve obtained with σ²-CASPT2. The imaginary shift curve is not shown as it is essentially overlapping to the σ²-CASPT2 one with a similar value of ε.