Rayleigh–Ritz method - Yukawa coulomb potential

Since the angular momentum operator only acts on the angular coordinates, it will yield 0 when acting on a function that doesn't depend on them.In summary, the testfunction given as \phi(\alpha, r)=\sqrt{(\frac{\alpha^3}{\pi})}exp(-\alpha r) and the potential V(r,\theta, \phi)=V(r)=-\frac{e^2}{r}exp(\frac{-r}{a}) are part of a larger problem that requires the calculation of the angular momentum operator \hat{L}^2 \phi . It is concluded that the answer is 0 as the testfunction does not depend on the angular coordinates that are acted upon by the operator
  • #1
AwesomeTrains
116
3
Hello everyone

Homework Statement


I have been given the testfunction [itex] \phi(\alpha, r)=\sqrt{(\frac{\alpha^3}{\pi})}exp(-\alpha r) [/itex], and the potential [itex] V(r,\theta, \phi)=V(r)=-\frac{e^2}{r}exp(\frac{-r}{a}) [/itex]
Given that I have to write down the hamiltonian (in spherical coordinates I assume), and I have to calculate the angular momentum operator [itex] \hat{L}^2 \phi [/itex]. (This is only a part of the whole problem. a) of a), b) and c) They should have used some other symbol for the testfunction than [itex]\phi[/itex], it's kinda confusing)

Homework Equations


Angular momentum operator in spherical coordinates.

The Attempt at a Solution


I guess the answer is 0, because [itex] \hat{L}^2 \phi [/itex] contains derivations of [itex]\theta, \phi[/itex] which the testfunction doesn't depend on. Is this true?
 
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  • #2
AwesomeTrains said:
Hello everyone

I guess the answer is 0, because [itex] \hat{L}^2 \phi [/itex] contains derivations of [itex]\theta, \phi[/itex] which the testfunction doesn't depend on. Is this true?
Yes that's true. Another way to look at it is to realize that the test function is proportional to ##Y_0^0##.
 

1. What is the Rayleigh-Ritz method?

The Rayleigh-Ritz method is a mathematical technique used to approximate the eigenvalues and eigenfunctions of a linear operator. It involves expressing the eigenfunctions as a linear combination of a set of trial functions and using a variational principle to minimize the energy functional.

2. What is the Yukawa coulomb potential?

The Yukawa coulomb potential, also known as the screened coulomb potential, is a mathematical model used to describe the interaction between two particles with electric charge. It takes into account the screening effect caused by the presence of other charged particles, resulting in a shorter range of interaction compared to the classic coulomb potential.

3. How does the Rayleigh-Ritz method work with the Yukawa coulomb potential?

The Rayleigh-Ritz method is used to approximate the eigenvalues and eigenfunctions of the Schrödinger equation that includes the Yukawa coulomb potential. This involves choosing a set of trial functions that satisfy the boundary conditions and using a variational principle to minimize the energy functional. The resulting approximate eigenvalues and eigenfunctions provide a good approximation of the true solutions to the Schrödinger equation.

4. What are the advantages of using the Rayleigh-Ritz method for the Yukawa coulomb potential?

The Rayleigh-Ritz method allows for a more accurate and efficient way to approximate the solutions to the Schrödinger equation with the Yukawa coulomb potential. It also allows for the inclusion of more complex potential functions, making it a versatile tool for solving a wide range of problems in quantum mechanics.

5. Are there any limitations to using the Rayleigh-Ritz method for the Yukawa coulomb potential?

One limitation of the Rayleigh-Ritz method is that the accuracy of the results depends on the choice of trial functions. If the chosen functions do not accurately represent the true eigenfunctions, the results may not be accurate. Additionally, the method can become computationally intensive for more complex systems or potentials.

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