Reducing eccentricity in black-hole binary evolutions with initial parameters from post-Newtonian inspiral

Standard choices of quasicircular orbit parameters for black-hole binary evolutions result in eccentric inspiral. We introduce a conceptually simple method, which is to integrate the post-Newtonian equations of motion through hundreds of orbits, and read off the values of the momenta at the separation at which we wish to start a fully general relativistic numerical evolution. For the particular case of nonspinning equal-mass inspiral with an initial coordinate separation of $D=11M$ we show that this approach reduces the eccentricity by at least a factor of 5 to $e<0.002$ as compared to using standard quasicircular initial parameters.