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Zeno is a software tool which computes physical properties for a particle or molecule. ITL has accelerated the software by a factor of 10,000x.


The Zeno software tool computes material, solution, and suspension properties for a specified particle shape or molecular structure using path-integral and Monte Carlo methods. The software was originally developed in Fortran77 at the Stevens Institute of Technology with support from NIST MML.  ITL was contacted to assist with modernizing the code and computationally accelerating it.

We first analyzed the original Fortran code and determined that the core computational algorithm was the Walk-on-Spheres stochastic algorithm, which has a nearest-neighbor spatial query in its innermost loop.  We rewrote the program in C++ to use a spatial data structure, Axially-Aligned Bounding Box (AABB) tree, and to take advantage of multicore and multi-node parallelism.  We demonstrated a speed-up factor of 10,000x over the original code. As a result of this speed-up, the software is now being used in ways which were not feasible before, such as to evaluate every time-step of a molecular-dynamics simulation.

Major Accomplishments

  • Accelerated original software by a factor of 10,000x
  • Publically released open-source version of the software


Created May 28, 2021, Updated June 11, 2021