Finding the Error in Computing Spherical Tensor of Rank 0 Using General Formula

In summary, there was a conversation about computing the spherical tensor ##T_0^{(0)}## using a general formula, but the result did not match the expected value. It was determined that there was a mistake in the Clebsch-Gordan coefficient, which should have been ##\frac{1}{\sqrt{3}}## instead of ##1##. The correct formula is ##T_0^{(0)} = \frac{1}{\sqrt{3}}(U_{1}^{(1)} V_{-1}^{(1)} + U_{0}^{(1)} V_{0}^{(1)} + U_{-1}^{(1)} V_{1}^{
  • #1
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TL;DR Summary
Coeffcient of spherical tensor of rank 0 from Clebsch_Gordan
This should be a trivial question. I am trying to compute the spherical tensor ##T_0^{(0)} = \frac{(U_1 V_{-1} + U_{-1} V_1 - U_0 V_0)}{3}## using the general formula (Sakurai 3.11.27), but what I get is:
$$
T_0^{(0)} = \sum_{q_1=-1}^1 \sum_{q_2=-1}^1 \langle 1,1;q_1,q_2|1,1;0,q\rangle U_{q_1}^{(1)} V_{q_2}^{(1)} \;\;\;\; \text{for} \; q = q_1 + q_2
$$
$$
T_0^{(0)} = \langle 1,1;1,-1|1,1;0,0\rangle U_{1}^{(1)} V_{-1}^{(1)} + \langle 1,1;0,0|1,1;0,0\rangle U_{0}^{(1)} V_{0}^{(1)} + \langle 1,1;-1,1|1,1;0,0\rangle U_{-1}^{(1)} V_{1}^{(1)}
$$
But this is ##T_0^{(0)} = \frac{(U_1 V_{-1} + U_{-1} V_1 - U_0 V_0)}{\sqrt{3}}##, if I read the Clebsch-Gordan coefficients correctly. Where did I make a mistake?
 
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  • #2
You made a mistake in the Clebsch-Gordan coefficient. The correct coefficient is $\langle 1,1;1,-1|1,1;0,0\rangle = \frac{1}{\sqrt{3}}$, not $1$. Therefore, you should have $$T_0^{(0)} = \frac{1}{\sqrt{3}}(U_{1}^{(1)} V_{-1}^{(1)} + U_{0}^{(1)} V_{0}^{(1)} + U_{-1}^{(1)} V_{1}^{(1)})$$
 

What is a spherical tensor of rank 0?

A spherical tensor of rank 0 is a mathematical object used in quantum mechanics to describe the properties of particles. It is a scalar quantity, meaning it has only one component and does not change under rotations.

What are the applications of spherical tensors of rank 0?

Spherical tensors of rank 0 are used in the study of atomic and molecular systems, as well as in the description of electromagnetic fields. They are also used in the analysis of nuclear magnetic resonance (NMR) spectra.

How is a spherical tensor of rank 0 different from tensors of other ranks?

Spherical tensors of rank 0 are different from tensors of other ranks in that they are invariant under rotations, meaning they do not change their value when the coordinate system is rotated. Tensors of higher ranks, on the other hand, have multiple components and their values change under rotations.

What is the relationship between spherical tensors of rank 0 and spherical harmonics?

Spherical tensors of rank 0 are closely related to spherical harmonics, which are mathematical functions used to describe the angular dependence of a wave function. In fact, spherical harmonics can be thought of as the basis functions for spherical tensors of rank 0.

How are spherical tensors of rank 0 used in quantum mechanics?

In quantum mechanics, spherical tensors of rank 0 are used to describe the properties of particles, such as their spin and magnetic moments. They are also used in the analysis of scattering processes and in the calculation of transition probabilities between different quantum states.

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