  We present results of first-principles calculations of the
frequency-dependent polarizabilities of all alkali atoms for light in the
wavelength range 300-1600 nm, with particular attention to wavelengths of
common infrared lasers. We parameterize our results so that they can be
extended accurately to arbitrary wavelengths above 800 nm. This work is
motivated by recent experiments involving simultaneous optical trapping of two
different alkali species. Our data can be used to predict the oscillation
frequencies of optically-trapped atoms, and particularly the ratios of
frequencies of different species held in the same trap. We identify wavelengths
at which two different alkali atoms have the same oscillation frequency.
