  The phase diagram of two-dimensional continuous particle systems is studied
using Event-Chain Monte Carlo. For soft disks with repulsive power-law
interactions $\propto r^{-n}$ with $n \gtrsim 6$, the recently established
hard-disk melting scenario ($n \to \infty$) holds: a first-order liquid-hexatic
and a continuous hexatic-solid transition are identified. Close to $n = 6$, the
coexisting liquid exhibits very long orientational correlations, and positional
correlations in the hexatic are extremely short. For $n\lesssim 6$, the
liquid-hexatic transition is continuous, with correlations consistent with the
Kosterlitz-Thouless-Halperin-Nelson-Yong (KTHNY) scenario. To illustrate the
generality of these results, we demonstrate that Yukawa particles likewise may
follow either the KTHNY or the hard-disk melting scenario, depending on the
Debye-H\"uckel screening length as well as on the temperature.

Statistical Mechanics;Soft Condensed Matter