A complete configuration interaction (CI) ground state surface for the H3+ system has been calculated using 5S and 3(P x,Py,Px) basis functions at each center. A total of 650 nuclear geometries has been considered which makes the new surface appropriate not only for scattering calculations, but also for the evaluation of the vibrational-rotational spectrum of the H3+ molecule. Significant deviations are found from the analytic Giese and Gentry potential used in many previous theoretical studies, especially for large and small nonequilibrium H-H separations which are important for vibrational excitation of the H2 molecule. Vibrational-rotational excitation cross sections have been calculated in the rotational sudden approximation where the vibrational degree of freedom is treated exactly by solving seven vibrationally coupled radial equations. The use of the new surface leads to increased vibrational excitation compared to previous calculations utilizing the same scattering approximation and to excellent agreement at 10 eV with the angle-dependent measurements of Hermann, Schmidt, and Linder. © 1980 American Institute of Physics.