On the accuracy of second-order Mّller-Plesset correlation energies

Accurate second-order Mّller-Plesset correlation energies are computed and compared with several semi-empirical estimates of the total correlation energies including those provided by Clementi, Anno and Teruya, and the recent results of Davidson, Froese and co-workers, for atoms with ten, twelve and eighteen electrons. Somewhat surprisingly, the MP2 correlation energies present what is considered to be in good agreement with the newest estimates, especially when the behaviour with the nuclear charge is examined.