  Many exoplanets in close-in orbits are observed to have relatively high
eccentricities and large stellar obliquities. We explore the possibility that
these result from planet-planet scattering by studying the dynamical outcomes
from a large number of orbit integrations in systems with two and three
gas-giant planets in close-in orbits (0.05 AU < a < 0.15 AU). We find that at
these orbital separations, unstable systems starting with low eccentricities
and mutual inclinations ($e\lesssim0.1$, $i\lesssim0.1$) generally lead to
planet-planet collisions in which the collision product is a planet on a
low-eccentricity, low-inclination orbit. This result is inconsistent with the
observations. We conclude that eccentricity and inclination excitation from
planet-planet scattering must precede migration of planets into short-period
orbits. This result constrains theories of planet migration: the semi-major
axis must shrink by 1-2 orders of magnitude without damping the eccentricity
and inclination.
