Calculation of the correlation energy of three electron systems of 20 to 25 electrons

Abstract

In this research the Hartree- Fock energies were calculated for three-electron systems (Ca+17 ,
Sc+18, Ti+19, V+20 , Cr+21 and Mn+22) have (Z=20-25) are obtained by an account the atomic
properties by using the Hartree- Fock method and Mathcad 14 program, the total expectation
value energy 〈EHF〉 and the correlation energy are important property account in this research and
when comparing the result with published results. It was found that there is a good agreement.