Spectroscopic term of ground state electron configuration of Carbon atom

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SUMMARY

The ground state electron configuration of the Carbon atom is 1s² 2s² 2p². The possible spectroscopic terms derived from the 2p² electrons include ^1S₀, ^1D₂, ^3P₀, ^3P₁, and ^3P₂. The initial derivation presented in the discussion incorrectly included additional terms due to a misunderstanding of the Pauli exclusion principle and the counting of multiplicities. The correct approach requires focusing on the multiplicities of the total angular momentum (J) rather than the spin (S) or orbital (L) separately.

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boyu
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The ground state electron configuration of Carbon atom is 1s^{2}2s^{2}2p^{2}

For the electrons, 1s^{2}2s^{2}, L=0, S=0

So only consider electrons of 2p^{2}, and

s_{1}=s_{2}=1/2 ---> S=0,1
l_{1}=l_{2}=1 ---> L=0,1,2

For S=0, L=0; J=0, so we have ^{1}S_{0}
For S=0, L=1; J=1, so ^{1}P_{1}
For S=0, L=2; J=2, so ^{1}D_{2}

For S=1, L=0; J=1, so ^{3}S_{1}
For S=1, L=1; J=0,1,2, so ^{3}P_{0}, ^{3}P_{1}, ^{3}P_{2}
For S=1, L=2; J=1,2,3, so ^{3}D_{1}, ^{3}D_{2}, ^{3}D_{3}

The above is based on my derivation. However, the correct answer is actually:
^{1}S_{0}, ^{1}D_{2}, ^{3}P_{0}, ^{3}P_{1}, ^{3}P_{2}

My question is: where are all the other possible terms? Where is wrong in my derivation:
 
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Not all the states you are constructing are compartible with the Pauli principle.
Namely you have six p-type spin orbitals and there are 15 (2 out of 6) possibilities.
Counting the multiplicities of the correct states you should also get 15.
The total number of states of your approach is 36 which would result from filling up the p orbitals with hypothetically distinguishable electrons.
 
How to get 15 from counting the multiplicities from correct states? The spin multiplicities are 1, 1, 3, 3 & 3.
 
You have to count the multiplicities of J not of S or L. The multiplicities of S and L are dispersed over states with different J.
 
Many thanks! ^_^
 

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