Jj coupling scheme and electronic configuration

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SUMMARY

The discussion focuses on determining possible terms (n1 j1, n2 j2, …) J for various electronic configurations using the jj coupling scheme. For the configurations 1s2, 1s2s, 1s22s22p, and 1s22s22p5, the calculated J values are derived from the coupling of angular momenta of electrons in different subshells. The terms for 1s2 are (1/2,1/2)0 and (1/2,1/2)1; for 1s2s, they remain the same. The more complex configurations yield terms such as (1/2,1,1,1,3/2,3/2)0 through (1/2,1,1,1,3/2,3/2)5 for 1s22s22p5, demonstrating the systematic approach to calculating total J values.

PREREQUISITES
  • Understanding of the jj coupling scheme in quantum mechanics
  • Familiarity with electron configurations and subshells
  • Knowledge of angular momentum coupling rules
  • Basic principles of quantum mechanics and atomic structure
NEXT STEPS
  • Study the jj coupling scheme in detail to understand its applications
  • Explore the concept of term symbols in atomic physics
  • Learn about the LS coupling scheme and compare it with jj coupling
  • Investigate the implications of electron configurations on atomic spectra
USEFUL FOR

This discussion is beneficial for students and professionals in physics, particularly those focusing on quantum mechanics, atomic structure, and spectroscopy. It is especially relevant for those studying electron configurations and angular momentum coupling in atoms.

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Homework Statement


Write all possible terms (n1 j1, n2 j2, …) J
for these electronic configurations (considering jj coupling scheme):
1s2
1s2s
1s22s22p
1s22s22p5

The Attempt at a Solution



1s2
I have two electrons in the s sub-shell,
since |l-s|<=j<=l+s then j1=1/2 and j2=1/2.
This gives possible J values of J=0,1 and the terms are

(1/2,1/2)0 (1/2,1/2)1


1s2s
one electron in 1s and one in 2s.
Again using a rule |l-s|<=j<=l+s gives j1=j2=1/2 for both electrons.
j1 and j2 can couple together go give total J=0,1 so the terms are again

(1/2,1/2)0 (1/2,1/2)1


So far I'm not sure that this is right, do I have to do this calculations with all electrons
or can I ignore completely filled shells ? But what about 1s2s then ? Also is my designation
of these terms like (j1,j2)J correct ?
 
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1s22s22pOne electron in 1s, two in 2s and two in 2p.Again using a rule |l-s|<=j<=l+s gives j1=1/2, j2,j3,j4=1 for all electrons in 2s and j5,j6=3/2 for electrons in 2p.These six can couple together to give total J=0,1,2,3 so the terms are(1/2,1,1,1,3/2,3/2)0 (1/2,1,1,1,3/2,3/2)1 (1/2,1,1,1,3/2,3/2)2 (1/2,1,1,1,3/2,3/2)31s22s22p5One electron in 1s, two in 2s, two in 2p and one in 5s.Again using a rule |l-s|<=j<=l+s gives j1=1/2, j2,j3,j4=1 for all electrons in 2s and j5,j6=3/2 for electrons in 2p and j7=1/2 for electron in 5s.These seven can couple together to give total J=0,1,2,3,4,5 so the terms are(1/2,1,1,1,3/2,3/2,1/2)0 (1/2,1,1,1,3/2,3/2,1/2)1 (1/2,1,1,1,3/2,3/2,1/2)2 (1/2,1,1,1,3/2,3/2,1/2)3 (1/2,1,1,1,3/2,3/2,1/2)4 (1/2,1,1,1,3/2,3/2,1/2)5
 

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