Henry A. Boateng - 2013-09-04

In molecular simulations it is sometimes necessary to compute the electrostatic potential at M target sites due to a disjoint set of N charged source particles. Direct summation is prohibitively expensive when M and N are large. Here we provide Fortran 90 code for two complementary fast summation treecode methods which reduce the cost. The standard particle-cluster treecode partitions the sources into an octree and applies a far-field approximation, while a recently developed cluster-particle treecode instead partitions the targets into an octree and applies a near-field approximation. The particle-cluster treecode is faster when the sources far outnumber the targets (N >> M), and conversely, the cluster-particle treecode is faster when the targets far outnumber the sources (M >> N). The algorithms are presented and compared in the paper: Boateng, H. A. and Krasny, R., Journal of Computational Chemistry (2013), DOI: 10.1002/jcc.23371 .

ACKNOWLEDGEMENTS:
This material is based upon work supported by the National Science Foundation under NSF Grants DMS-0854870 and DMS-0915057. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.