P H = · + V 2m 1. Starting with the canonical commutation relations for position and momentum [Âi, Âj] = [Îi, Îj] = 0 [Îi‚Âj] = −[ƒ‚ Îi] = −iħdij work out the following commutators, use the definition of L₂ below (Q2). [L, x] = iħy, [L, y] = − iħx, [L, z] = 0, [LPx] = iħpy, [L₂,Py] = − ihpx, [L„P₂] = 0 2. Use these results to obtain [L, L] = iħL, directly from - Lx = YPz− ZPy, Ly = ZPx − xp² L₁ = xPy — YPx 3. Use the results from Q1 to evaluate the commutators [L₂,r²] & [L₂,p²] where: 2 ༡ r² = x² + y² + z² & p² = p²+p²+p² & [L₂,x²] = x[L₂,x] + [L₂, x]x 4. Show that the Hamiltonian (H, see top right) commutes with Lz and L, provided V depends only on r and not 0 or Q. For L², first show that Lx and p2 commute, you can assume the same for Ly. This is similar to Q3 for Lz. h Lx = [ д д - sin op ᏧᎾ cos cot 0- дф Ly = д ħ д h d cos . - sin & cot 0. L₂ = ᎧᎾ дф і дф

Question

can you help me solve question 4 please

P
H = ·
+ V
2m
1. Starting with the canonical commutation relations for position and momentum
[Âi, Âj] = [Îi, Îj] = 0
[Îi‚Âj] = −[ƒ‚ Îi] = −iħdij
work out the following commutators, use the definition of L₂ below (Q2).
[L, x] = iħy, [L, y] = − iħx, [L, z] = 0,
[LPx] = iħpy, [L₂,Py] = − ihpx, [L„P₂] = 0
2. Use these results to obtain [L, L] = iħL, directly from
-
Lx = YPz− ZPy, Ly = ZPx − xp² L₁ = xPy — YPx
3. Use the results from Q1 to evaluate the commutators [L₂,r²] & [L₂,p²]
where:
2
༡
r² = x² + y² + z² & p² = p²+p²+p² & [L₂,x²] = x[L₂,x] + [L₂, x]x
4. Show that the Hamiltonian (H, see top right) commutes with Lz and L, provided V
depends only on r and not 0 or Q. For L², first show that Lx and p2 commute, you can
assume the same for Ly. This is similar to Q3 for Lz.
h
Lx =
[
д
д
- sin op
ᏧᎾ
cos cot 0-
дф
Ly
=
д
ħ
д
h d
cos .
-
sin & cot 0.
L₂ =
ᎧᎾ
дф
і дф
Transcribed Image Text:P H = · + V 2m 1. Starting with the canonical commutation relations for position and momentum [Âi, Âj] = [Îi, Îj] = 0 [Îi‚Âj] = −[ƒ‚ Îi] = −iħdij work out the following commutators, use the definition of L₂ below (Q2). [L, x] = iħy, [L, y] = − iħx, [L, z] = 0, [LPx] = iħpy, [L₂,Py] = − ihpx, [L„P₂] = 0 2. Use these results to obtain [L, L] = iħL, directly from - Lx = YPz− ZPy, Ly = ZPx − xp² L₁ = xPy — YPx 3. Use the results from Q1 to evaluate the commutators [L₂,r²] & [L₂,p²] where: 2 ༡ r² = x² + y² + z² & p² = p²+p²+p² & [L₂,x²] = x[L₂,x] + [L₂, x]x 4. Show that the Hamiltonian (H, see top right) commutes with Lz and L, provided V depends only on r and not 0 or Q. For L², first show that Lx and p2 commute, you can assume the same for Ly. This is similar to Q3 for Lz. h Lx = [ д д - sin op ᏧᎾ cos cot 0- дф Ly = д ħ д h d cos . - sin & cot 0. L₂ = ᎧᎾ дф і дф
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