  Studying compact star binaries and their mergers is integral to determining
progenitors for observable transients. Today, compact-star mergers are
typically studied via state-of-the-art computational fluid dynamics codes. One
such numerical technique, Smoothed Particle Hydrodynamics (SPH), is frequently
chosen for its excellent mass, energy, and momentum conservation. The natural
treatment of vacuum and the ability to represent highly irregular morphologies
make SPH an excellent tool for the study of compact-star binaries and mergers.
For many scenarios, including binary systems, the outcome of simulations is
only as accurate as the initial conditions. For SPH, it is essential to ensure
that the particles are distributed regularly, representing the initial density
profile but without long-range correlations. Particle noise in the form of
high-frequency local motion and low-frequency global dynamics must be damped
out. Damping the latter can be as computationally intensive as the actual
simulation. We discuss a new and straightforward relaxation method,
Halted-Pendulum Relaxation (HPR), to remove global oscillation modes of SPH
particle configurations. In combination with effective external potentials
representing gravitational and orbital forces, we show that HPR has an
excellent performance in efficiently relaxing SPH particles to the desired
density distribution and removing global oscillation modes. We compare the
method to frequently used relaxation approaches and test it on a white dwarf
binary model at its Roche lobe overflow limit. We highlight the importance of
our method in achieving accurate initial conditions and its effect on achieving
circular orbits and realistic accretion rates when compared with other general
relaxation methods.
