Efficient computation of optical forces with the coupled dipole method

We present computational techniques to compute in an efficient way optical forces on arbitrary nanoobjects using the coupled dipole method. We show how the time of computation can be reduced by several orders of magnitude with the help of fast-Fourier-transform techniques. We also discuss the influence of different formulations of the electric polarizability of a small scatterer on the accuracy and robustness of the computation of optical forces