I point out a confusion that is rather common in optical forces, i.e., that the time average of the Lorentz force on a dipole (for a harmonic time-varying field) is sometimes assumed to be a gradient force that is due to omission of the radiative reaction term in the polarizability of the dipole.
© 2004 Optical Society of America
Patrick C. Chaumet, "Comment on “Trapping Force, Force Constant, and Potential Depths for Dielectric Spheres in the Presence of Spherical Aberrations”," Appl. Opt. 43, 1825-1826 (2004)