Discussion
In this study we mainly concentrated on the calculation of the Self
consistent field calculation for Cr atom where the expected
configuration is different from the observed one. As is already
explained in the text the observed ground term and the expected ones are7S and 5D respectively. The total
energy values for these representations determine the relative position
of the states of one configuration to those of another. It is obvious
from the table 1 that all calculations suggest the 7S
representation should lie lowest which represents a deviation from
Madelung’s rule.
The interaction between the nd orbitals and the core-electron orbitals
might be the reason for this exception, the shells are seems to be
filled according to the hydrogenic rule rather than the first part of
Madelung’s rule, when there are more than four ad-shell electrons the
quantum number n might have the dominant role.
Cr atom’s electron configuration that is different than the Madelung’s
rule might be not only due to the Hund rules, but also with rhe
phenomena known as ‘spin correlation’. This effect should not be
considered with itself, it should be taken into account with the Hund’s
first rule which states that the lowest energy atomic state is the one
that maximizes the total spin quantum number for the electrons in the
open subshell.