This interface implements MP2 extrapolation to the complete basis set limit and an optional
higher-order correction (e.g. CCSDT(T), MP2.5 - see the examples).
A following scheme is used:
- HF energy is taken from the MP2 calculation in the larger basis set
- MP2 correlation energy is extrapolated using the formula of Halkier and Helgaker[1]
- Higher-order correction (the result - MP2 energy) is calculated in a smaller basis set
- Halkier, A.; Helgaker, T.; Jørgensen, P.; Klopper, W.; Koch, H.; Olsen, J.; Wilson, A. K. Basis-Set Convergence in Correlated Calculations on Ne, N2, and H2O. Chem. Phys. Lett. 1998, 286, 243–252.