  Evaluation of pair potentials is critical in a number of areas of physics.
The classicalN-body problem has its root in evaluating the Laplace potential,
and has spawned tree-algorithms, the fast multipole method (FMM), as well as
kernel independent approaches. Over the years, FMM for Laplace potential has
had a profound impact on a number of disciplines as it has been possible to
develop highly scalable parallel algorithm for these potential evaluators. This
is in stark contrast to parallel algorithms for the Helmholtz (oscillatory)
potentials. The principal bottleneck to scalable parallelism are operations
necessary to traverse up, across and down the tree, affecting both computation
and communication. In this paper, we describe techniques to overcome
bottlenecks and achieve high performance evaluation of the Helmholtz potential
for a wide spectrum of geometries. We demonstrate that the resulting
implementation has a load balancing effect that significantly reduces the
time-to-solution and enhances the scale of problems that can be treated using
full wave physics.
