  The high-multiplicity exoplanet systems are generally more tightly packed
when compared to the solar system. Such compact multi-planet systems are often
susceptible to dynamical instability. We investigate the impact of dynamical
instability on the final orbital architectures of multi-planet systems using
N-body simulations. Our models initially consist of six to ten planets placed
randomly according to a power-law distribution of mutual Hill separations. We
find that almost all of our model planetary systems go through at least one
phase of dynamical instability, losing at least one planet. The orbital
architecture, including the distributions of mutual Hill separations, planetary
masses, orbital periods, and period ratios, of the transit-detectable model
planetary systems closely resemble those for the multi-planet systems detected
by Kepler. We find that without any formation-dependent input, a dynamically
active past can naturally reproduce important observed trends including
multiplicity-dependent eccentricity distribution, smaller eccentricities for
larger planets, and intra-system uniformity. On the other hand, our
transit-detectable planet populations lack the observed sub-population of
eccentric single-transiting planets, pointing towards the Kepler dichotomy.
These findings indicate that dynamical instabilities may have played a vital
role in the final assembly of sub-Jovian planets.
