We present the results of a neutron scattering study of the high energy phonons in the superconducting graphite intercalation compound CaC_6. The study was designed to address hitherto unexplored aspects of the lattice dynamics in CaC_6, and in particular any renormalization of the out-of-plane and in-plane graphitic phonon modes. We present a detailed comparison between the data and the results of density functional theory (DFT). A description is given of the analysis methods developed to

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... nt for the highly-textured nature of the samples. The DFT calculations are shown to provide a good description of the general features of the experimental data. This is significant in light of a number of striking disagreements in the literature between other experiments and DFT on CaC_6. The results presented here demonstrate that the disagreements are not due to any large inaccuracies in the calculated phonon frequencies.