HIGH-PRECISION ATOMIC COMPUTATIONS FROM FINITE-ELEMENT TECHNIQUES - 2ND-ORDER CORRELATION ENERGIES OF RARE-GAS ATOMS

The p-version finite element method for atomic computations [J. Chem. Phys. 91, 7030 (1989)] has been implemented within the frame of second-order Moller-Plesset theory and used to calculate correlation energies of the rare-gas atoms from He to Rn. The calculation proceeds through a sequence of levels of computation that is systematic and hierarchic in nature and helps to estimate the error of the final values. It is possible to include virtual orbitals of very high angular momentum (l(max) = 12) even for the heaviest elements; so very accurate results can be obtained. Comparison with the most accurate values found in the literature indicates that our FEM-MP2 method competes very well with any other method, even with Kutzelnigg's MP2-R12 method [J. Chem. Phys. 94, 2002 (1991)], especially in the case of heavy atoms. The results presented here could be the most accurate published so far.