  Recently, Pantina and Furst (Phys. Rev. Lett., 94(13), 138301, 2005)
experimentally demon- strated that there are tangential forces between bonded
colloidal particles and that bonds between colloidal particles are capable of
supporting bending moments. We introduce a model to be used in computer
simulations that describes these tangential interactions. We show how the model
parame- ters can be determined from experimental data. Simulations using the
model are able to reproduce the measurement of Pantina and Furst. Application
of the model to an aggregate with fractal structure leads to more realistic
behavior than using classical approaches only.
