Electron correlation effects in the 4f14 shell

Abstract

AbstractSecond‐order Rayleigh–Schrödinger Hartree–Fock perturbation theory is applied to evaluate the correlation energy for the 4f14 shell of Yb. The partial‐wave (PW) increments to the pair energies, and the total correlation energy are calculated using first‐order radial pair functions obtained as the solution of two‐dimensional differential equations. These equations are solved using the Chalmers University version of the finite difference method. The total second‐order correlation energy amounts to 0.89573 hartree. The results for the pair energies, which are close to the all‐external pair energies, are compared with related CI values. It turns out that the correlation effects within the 4f shell of rare‐earth systems are dominated by the all‐external effects. The ff and gg PWS are dominant in the description of the correlation effects in the 4f shell and provide 80% of the total correlation energy. Next in importance are the dd, hh, and dg PWS which provide 12% of the total correlation energy.