The MNPBEM Toolbox by Ulrich Hohenester is a flexible simulation toolkit for the calculation of the electromagnetic properties of plasmonic nanoparticles. The toolbox has been implemented with Matlab classes. Maxwell's equations are solved using a boundary element method (BEM) approach.
The latest version of the toolbox now also includes iterative solvers and H-matrices for the simulation of large nanoparticles (consisting of a few 10 000 boundary elements).