Ground state potential energy curves for He2, Ne2, Ar2, He–Ne, He–Ar, and Ne–Ar: A coupled-cluster study

Potential energy curves for three homonuclear $({\mathrm{He}}_2,$ ${\mathrm{Ne}}_2,$ ${\mathrm{Ar}}_2)$ and three heteronuclear $(\mathrm{He–Ne},$ $\mathrm{He–Ar},$ $\mathrm{Ne–Ar})$ rare gas dimers are presented. The curves were calculated using several correlation consistent basis sets and the supermolecule single and double excitation coupled-cluster theory with noniterative perturbational treatment of triple excitations, CCSD(T). The most accurate results were obtained with the aug-cc-pV5Z basis set supplemented with an additional $\text{(3s3p2d2f1g)}$ set of bond functions. The results obtained with a smaller $\mathrm{aug}-\mathrm{cc}-\mathrm{pVQZ}\text{+(3s3p2d2f1g)}$ basis set are almost as accurate. Both basis sets give results in better agreement with potentials based on experiments than the recent results obtained with larger d-aug-cc-pV6Z and t-aug-cc-pV6Z basis sets but without bond functions. For each complex and each basis set a fitted potential energy curve is given. In addition, for each complex, with the exception of ${\mathrm{He}}_2,$ the values of $R_e,$ $D_e,$ $B_0,$ $D_0,$ and ${\mathrm{〈R〉}}_0$ are given. For ${\mathrm{He}}_2$ no bound states were found so only the values of $R_e$ and $D_e$ are presented. For ${\mathrm{Ne}}_2,$ ${\mathrm{Ar}}_2,$ and Ne–Ar the calculated frequencies of vibrational and pure rotational transitions are shown to be in good agreement with the experimental results.