# What is Ls coupling: Definition and 11 Discussions

In quantum mechanics, the procedure of constructing eigenstates of total angular momentum out of eigenstates of separate angular momenta is called angular momentum coupling. For instance, the orbit and spin of a single particle can interact through spin–orbit interaction, in which case the complete physical picture must include spin–orbit coupling. Or two charged particles, each with a well-defined angular momentum, may interact by Coulomb forces, in which case coupling of the two one-particle angular momenta to a total angular momentum is a useful step in the solution of the two-particle Schrödinger equation.
In both cases the separate angular momenta are no longer constants of motion, but the sum of the two angular momenta usually still is. Angular momentum coupling in atoms is of importance in atomic spectroscopy. Angular momentum coupling of electron spins is of importance in quantum chemistry. Also in the nuclear shell model angular momentum coupling is ubiquitous.In astronomy, spin–orbit coupling reflects the general law of conservation of angular momentum, which holds for celestial systems as well. In simple cases, the direction of the angular momentum vector is neglected, and the spin–orbit coupling is the ratio between the frequency with which a planet or other celestial body spins about its own axis to that with which it orbits another body. This is more commonly known as orbital resonance. Often, the underlying physical effects are tidal forces.

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1. ### A Vector sum schemes for LS coupling & jj coupling

The difference between light and very heavy atoms reflects itself in these two schemes. My question is why one scheme for the vector sum is necessarily the right & suitable sum model for one case, and the 2nd scheme suits the 2nd case ? In other words, why & how the relative magnitude of the...
2. ### I LS coupling and spin orbit interaction

Why do you need a weak spin orbit interactions in individual electrons in order to use the LS coupling? From what I know, we are free to combined angular momentum whenever [L1, L2]=0 and this should be true on the orbital angular momentum (and spin) of the electrons because they are...
3. ### I In what cases (precisely) are Hund's rules valid?

I can't find on any good source (such as a textbook) a precise specification about the cases when Hund's rules (especially Hund's third rule) for an electronic configuration of atom are valid (the rules help to select the lowest energy state of a configuration). As far as I understood: Hund’s...
4. ### What are S, L and J for the following states....?

Homework Statement What are S, L and J for the following states: ##^1S_0, ^2D_{5/2} ^5F_1, ^3F_4## Homework Equations The superscript is defined as: 2S + 1 The subscript is defined as: J = L + S The letter denotes the angular momentum number (s, p, d, f...) starting at s = 0. The Attempt at a...
5. ### A Russel-Saunders Coupling in Extended Oxides

Hey all, I am a graduate student (in chemistry) working on oxide crystals. Our group has a SQUID magnetometer which we use for magnetic property measurements. The other day a fellow student and myself got into a discussion about LS coupling and crystal electric fields. I know that CEF will...
6. ### Exchange symmetry when adding angular momentum and in LS coupling?

When you add two angular momentum states together, you get states which have exchange symmetry i.e. the highest total angular momentum states (L = l1 + l2) will be symmetric under the interchange of the two particles, (L = l1 + l2 - 1) would be anti-symmetric...and the symmetry under exchange...
7. ### LS coupling and calculating the total angular momentum

hi all, these days i m going through Arther Beiser's modern physics book where i read about the total angular momentum in many electron atoms..now i could understand the LS coupling and spin orbit effect how they combine to form total angular momentum but if i m given the magnitude of L=2...
8. ### Finding components of 2s2p configuration using LS coupling

Homework Statement The lowest excited states of the Be atom correspond to a 2s2p configuration of optically active electrons. What 2s+1Lj components originate in this configuration? Assume that Hund's rules hold for the multiplet and deduce the ordering of the energy levels. Refer to a table...
9. ### Rare-earth energy levels from LS coupling

Hey all, Is there a way to rank the energy levels of a rare-earth ion in order of increasing energy just from the spectroscopic terms? Nd3+ has an electron configuration of [Xe]4f^3, which produces energy levels such as 4I, 4F, 2H, 4S, 2G, 4G, 2D, etc from the electrostatic interaction...
10. ### Spin orbit interaction and LS coupling

I hope someone can help me out here. I am having difficulty understanding what the difference is between the spin orbit interaction and LS coupling scheme in atoms. I know the spin orbit interaction (or spin orbit coupling) is due to the interaction of say an electron's spin with it's orbital...
11. ### LS coupling for identical electrons

Let's say I'm considering the 3p^2 electrons. From the Pauli Exclusion Principle, we know that two electrons cannot have the same state, which in this case means ml and ms cannot both be the same for each electron. What this means is that the following 6 terms must not be allowed: m_{l1}...