This project seeks to improve modeling of the final stages of planet formation by probing how planetary orbits change over time due to two possible physical causes: planet-planet gravitational scattering and tidal interactions. Gravitational interactions between planets can induce significant orbital changes, such as increased eccentricities, collisions between planets, and even ejection of planets from the system. Orbits may be also altered due to tidal forces between closer-in planets and their host star. Since the scattering and tidal effects depend critically on the planetary masses involved, the PI will also model the mass-frequency distribution of planetary systems. In particular, he will study the relationship between the initial planetary mass function (before scattering), and the observed planetary mass function of known planetary systems. The PI's modeling effort will run a series of N-body simulations of the gravitational interactions between planets, and tidal evolution to constrain how well these effects can explain observations of known exoplanet orbits and their current mass distributions. The PI will mentor undergraduate students in research who are participating in the University of Washington's ''Pre-Major in Astronomy Program.''