Coupled-cluster interaction energies for eleven weakly interacting complexes involving rare gas atoms, water, and methane are computed using large correlation-consistent basis sets augmented with bond functions. The estimates of the coupled-cluster singles, doubles, and noniterative triples [CCSD(T)] complete basis set limit (CBS) are obtained using conventional and explicitly correlated (F12) approaches. It is shown that both bond functions and the F12 approach significantly speed up the basis set convergence of CCSD(T) interaction energies. However, the extent of improvement varies with the character of the interactions � the F12 method works best for polar dimers while for dispersion-dominated complexes the addition of bond functions is more efficient. In all cases, the most accurate values are obtained using both bond functions and the F12 approach. The agreement between large-basis conventional and explicitly correlated results allows us to assess the importance of different residual approximations present in the popular CCSD(T)-F12 implementations.

Basis set converged weak interaction energies from conventional and explicitly correlated coupled-cluster approach

245th National Meeting (2013)

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