  Rate coefficients for inelastic collisions between Li and H atoms covering
all transitions between the asymptotic states
Li(2s,2p,3s,3p,3d,4s,4p,4d,4f)+H(1s) and Li^+ +H^- are presented for the
temperature range 2000-8000 K based on recent cross-section calculations. The
data are of sufficient completeness for non-LTE modelling of the Li I 670.8 nm
and 610.4 nm features in late-type stellar atmospheres. Non-LTE radiative
transfer calculations in both 1D and 3D model atmospheres have been carried out
for test cases of particular interest. Our detailed calculations show that the
classical modified Drawin-formula for collisional excitation and de-excitation
(Li*+H <-> Li*'+H) over-estimates the cross-sections by typically several
orders of magnitude and consequently that these reactions are negligible for
the line formation process. However, the charge transfer reactions collisional
ion-pair production and mutual neutralization (Li*+H <-> Li^+ +H^-) are of
importance in thermalizing Li. In particular, 3D non-LTE calculations of the Li
I 670.8 nm line in metal-poor halo stars suggest that 1D non-LTE results
over-estimate the Li abundance by up to about 0.1 dex, aggrevating the
discrepancy between the observed Li abundances and the primordial Li abundance
as inferred by the WMAP analysis of the cosmic microwave background.
