A relativistic ab initio model potential ͑AIMP͒ for Pt, Au, and Hg atoms has been developed using a relativistic scheme by eliminating small components ͑RESC͒ in which the 5p, 5d, and 6s electrons are treated explicitly. The quality of new RESC-AIMP has been tested by calculating the spectroscopic properties of the hydrides of these elements using the Hartree-Fock and coupled cluster with singles and doubles ͑CCSD͒ methods. The agreement with reference all-electron RESC calculations is excellent. The RESC-AIMP method is applied successfully in the investigation of the spectroscopic constants of Au 2 and Hg 2 using the CCSD method with a perturbative estimate of the contributions of triples. The ground state of Pt 2 is also determined by RESC-AIMP with the second-order complete active space perturbation method. The results show that scalar relativistic effects on the valence properties are well described by the RESC-AIMP method. The effect on the basis set superposition error on the spectroscopic constants is also examined.