  Recent model simulations discovered unexpected non-monotonic features in the
wear-free dry phononic friction as a function of the sliding speed. Here we
demonstrate that a rather straight- forward application of linear-response
theory, appropriate in a regime of weak slider-substrate in- teraction,
predicts frictional one-phonon singularities which imply a non-trivial
dependence of the dynamical friction force on the slider speed and/or coupling
to the substrate. The explicit formula which we derive reproduces very
accurately the classical atomistic simulations when available. By modifying the
slider-substrate interaction the analytical understanding obtained provides a
practical means to tailor and control the speed dependence of friction with
substantial freedom.
