Kinetic and potential energy of isoelectronic atomic ions from density functional theory compared with exact values

The performance of the Fock exchange and the two most common Becke exchange functionals, B88 and B3, in combination with Perdew and Wang's correlation functional (PW91) has been studied for highly charged atomic ions. The stu dy focuses on the accuracy of the components of total energy: kinetic and p otential energy. It is found that Becke's exchange functionals introduce a significant error in the kinetic and nuclear attraction energy for most ion s studied, and the use of these exchange functionals might lead to inaccura te momentum distributions when their Kohn-Sham orbitals are transformed to momentum space.