New computational techniques to simulate Light Scattering from arbitrary particles

The Coupled Dipole method, as originally formulated by Purcell and Pennypacker, is a very powerful method to simulate the Elastic Light Scattering from arbitrary particles. This method however has one major drawback: if the size of the particles grows, or if scattering from an ensemble of randomly oriented particles has to be simulated, the computational demands of the Coupled Dipole method soon become too high. In this paper we present two new computational techniques to resolve this problem. First we have implemented the Coupled Dipole method on a Massively Parallel Computer. The parallel efficiency can be very close to one, implying that attained computational speed scales perfectly with the number of processors. Secondly we propose to reduce the computational complexity of the Coupled Dipole method by including ideas from the so-called fast multipole methods (hierarchical algorithms) into the Coupled Dipole method. In this way the calculation time can be decreased with orders of magnitude.