The structure and ground state dynamics of the interaction Ne:HI have been investigated. The potential surface from ab initio molecular orbital calculation was morphed to yield a fit to experimental data. This intermolecular potential results in a ground state Ne-20:HI with R-cm = 4.1018(1) Angstrom. and (P-2 (cos theta')) = 0.12527(1), a nearly free rotor state. For Ne-20:DI, R-cm was 3.9616 (1) A with a value of [P-2(cos theta') = 0.41110(1) corresponding to an angle theta' = 141.20(1) in the isomeric structure. Ne-ID. Ground state characteristics are compared with those determined for Ar:HI and Kr:HI. and predicted for Ne:HI. (C) 2002 Published by Elsevier Science B.V.