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Homework Help: Determening allowed states in atoms

  1. Oct 20, 2005 #1
    there is one thing about atomic states I don't understand. I try to look at what states are possible for a np^2 configuration (that is, all lower shells are filled and don't contribute to the case). For example my textbook says that the [tex]~^1 P[/tex] state is not allowed because of the Pauli principle.
    But now, let's have a look at what [tex]^1 ~P[/tex] means:
    L = 1
    S = 0
    The spins are clearly anti-parallel. For L = 1 we have M_L = -1,0,1. I don't see any problem finding m_l's adding up to those M_L's without breaking the Pauli principle. So what am I not getting?
  2. jcsd
  3. Oct 21, 2005 #2


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    Er... unless I misunderstand your notation, for n=1, you only have L=0 as the only possible angular momentum state. L=1 doesn't exist. Only for n=2 do you have L=0 and 1.

  4. Oct 21, 2005 #3
    No I don't mean n=1 but rather 2S+1 = 1. I tried to hang the "1" a bit higher with tex-code, but it didn't work out perfectly I guess. To clarify: with upper case I mean the total spin/orbital angular momentum of all the electrons and with lower case spin/orbital angular momentum of an individual electron.
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