An ab initio potential energy surface (PES) for the ground state（12 A′）of the chemical reaction Ar+H2 + →ArH++H has been constructed from a set of accurate ab initio data,which we have computed using the coupled-cluster theory including all single and double excitations plus perturbative corrections for the triples UCCSD(T) with a large orbital basis set of aug-cc-pV5Z.