with population equally smeared on the d orbitals,
t3ðnþmÞ=5
2g e2ðnþmÞ=5
g . The 10Dq gap can be approximated, in first instance,
as the difference between the groundstate configuration
GS = tn
2gemgand a transition state TS1 = tn1
2g emþ1
g comprising the electron
promotion. We will discuss later about other conventions to
estimate 10Dq.