Scalar relativistic coupled cluster calculations for the potential energy curve and the distance dependence of the static dipole polarizability tensor of Hg-2 are presented and compared with current experimental work. The role of the basis set superposition error for the potential energy curve and the dipole polarizability is discussed in detail. Our recently optimized correlation consistent valence basis sets together with energy adjusted pseudopotentials are well suited to accurately describe the van der Waals system Hg-2. The vibrational-rotational analysis of the best spin-orbit corrected potential energy curve yields r(e)=3.74 A, D-0=328 cm(-1), omega (e)=18.4 cm(-1), and omega (e)x(e)=0.28 cm(-1) in reasonable agreement with experimental data (r(e)=3.69+/-0.01 Angstrom, D-e=380+/-25 cm(-1), omega (e)=19.6+/-0.3 cm(-1) and omega (e)x(e)=0.25+/-0.05 cm(-1)). We finally present a scaled potential energy curve of the form Sigma (j)a(2j)r(-2j) which fits the experimental fundamental vibrational transition of 19.1 cm-1 and the form of our calculated potential energy curve best (r(e)=3.69 Angstrom, D-0=365 cm(-1), omega (e)=19.7 cm(-1), and omega (e)x(e)=0.29 cm(-1)). We recommend these accurate two-body potentials as the starting point for the construction of many-body potentials in dynamic simulations of mercury clusters.