Computational modelling of optical tweezers offers opportunities for
the study of a wide range of parameters such as particle shape and
composition and beam profile on the performance of the optical trap,
both of which are of particular importance when applying this technique to arbitrarily shaped biological entities. In addition,
models offer insight into processes that can be difficult to experimentally measure with sufficient accuracy. This can be invaluable for the proper understanding of novel effects within optical tweezers. In general, we can separate methods for computational modelling of optical tweezers into two groups: approximate methods such as geometric optics or Rayleigh scattering, and exact methods, in which the Maxwell equations are solved. We discuss the regimes of applicability of approximate methods, and consider the relative merits of various exact methods. The T-matrix method, in particular, is an attractive technique due to its efficiency for repeated calculations, and the simplicity of determining the optical force and torque. Some example numerical results are presented.