The calculation method is based on Mie theory and can only be used to calculate optical scattering force on a spherical particle illuminated by a plane wave.

The equations for calculate radiation pressure efficiency Qpr is based on this paper:

Light scattering by spherical particles: Radiation pressure, asymmetry factor, and extinction cross section. (PDF)

Figure below shows the calculated optical radiation force as a function of particle radius. Incident plane wave has a wavelength of 1064 nm and the surrounding medium is water. My Python code for the calculation can be found here.

The equations for calculate radiation pressure efficiency Qpr is based on this paper:

Light scattering by spherical particles: Radiation pressure, asymmetry factor, and extinction cross section. (PDF)

Figure below shows the calculated optical radiation force as a function of particle radius. Incident plane wave has a wavelength of 1064 nm and the surrounding medium is water. My Python code for the calculation can be found here.