  We present validation and results from a simulation of the Fermilab Tevatron
including multiple beam dynamics effects. The essential features of the
simulation include a fully 3D strong-strong beam-beam particle-in-cell Poisson
solver, interactions among multiple bunches and both head-on and long-range
beam-beam collisions, coupled linear optics and helical trajectory consistent
with beam orbit measurements, chromaticity and resistive wall impedance. We
validate individual physical processes against measured data where possible,
and analytic calculations elsewhere. Finally, we present simulations of the
effects of increasing beam intensity with single and multiple bunches, and
study the combined effect of long-range beam-beam interactions and transverse
impedance. The results of the simulations were successfully used in Tevatron
operations to support a change of chromaticity during the transition to
collider mode optics, leading to a factor of two decrease in proton losses, and
thus improved reliability of collider operations.
