Figure 3: Illustration of partial preoptimization employed for accurate description of the asymptotic region. The fixed 400 points are shown by black dots. The optimized 100 points are shown by red dots. (a) Energies from the old PES. (b) Energies obtained in this work at the CBS level. The additional 70 points placed in the critical parts of the PES a posteriori are shown by green dots. The corresponding MEPs are shown by blue lines.