  For like charged colloidal particles two mechanisms of attraction between
them survive when the interparticle distance is larger than the Debye screening
length. One of them is the conventional van der Waals attraction and the second
one is the attraction mechanism mediated by thermal fluctuations of particle
positions. The latter is related to an effective variable mass (Euler mass) of
the particle produced by a fluid motion. The most stronger attraction potential
(up to the value of temperature T) corresponds to a situation of uncharged
particles and a relatively large Debye screening length. In this case the third
mechanism of attraction enters the game. It is mediated by thermal fluctuations
of a fluid density.
