OTDDA: A discrete dipole approximation framework for computing optical scattering and related forces on arbitrarily shaped particles in optical tweezers

Optical tweezers are a fundamental tool for micro- and nano-object manipulation, yet accurate and efficient calculation of scattering fields and forces for particles with arbitrary shapes remains challenging. Here we introduce an efficient computational framework for optical tweezers based on discrete dipole approximation, termed OTDDA, which enables precise calculation of electromagnetic field distributions and optical forces for particles of arbitrary shapes under complex illumination conditions. Moreover, by coupling electromagnetic simulation with heat conduction equations, OTDDA can also compute temperature distributions and photophoretic forces in absorptive particles in atmospheric environments. The numerical stability and accuracy of the framework are validated against standard Mie theory for non-absorptive spherical particles. The MATLAB-based code for OTDDA is released as an open-source project to support reproducible research in optical trapping and the broader field of light-matter interactions.