Figure 8.

Critical angle ${\vartheta }_0$ at which the central force changes sign as a function of the applied field $\xi$. Solid curves are MDM predictions for $\phi =0.3$, $l=1.4$ and different $\lambda$ (see legend). The dashed horizontal line is the classical LDM value ${\vartheta }_0=arccos(1/\sqrt{3})\simeq 54.7°$.