Using Generalization of Bohr Rule for 1D Harmonic Oscillator

In summary, the generalization of the Bohr rule to periodic motion states that the closed line integral of momentum and position is equal to nh = 2∏nh(bar). Using this rule, it can be shown that the spectrum for a one-dimensional harmonic oscillator is E = nh(bar)ω, where E is the energy, n is a positive integer, and ω is the angular frequency. To find this result, the integral of momentum must be taken and solved for E, with the endpoints where the kinetic energy is zero being 0 and an undetermined point. After accounting for the trip back in the closed loop, the integral can be multiplied by 2 to get the final result.
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Homework Statement



The generalization of the bohr rule to periodic motion more general than circular orbit states that:
∫p.dr = nh = 2∏nh(bar).

the integral is a closed line integral and the "p" and "r" are vectors

Using the generalized rule (the integral above), show that the spectrum for the one-dimensional harmonic oscillator, for which E = p^2/2m + (1/2)m*ω^2*x^2, is E = nh(bar)ω.

Homework Equations



px = nh(bar)
p= m*ω*x

The Attempt at a Solution



I have put p in terms of E and x, to get p=sqrt(2mE-m^2*ω^2*x^2).

I took the indefinite integral of that expression with respect to x, since the problem is one-dimensional, and got (1/2)x*sqrt(2mE-m^2*ω^2*x^2) + (E*arctan((m*ω*x)/(sqrt(2mE-m^2*ω^2*x^2))))/ω. Both WolframAlpha and my TI-89 give this same answer.

I realize here that, replacing sqrt(2mE-m^2*ω^2*x^2) with p and p with m*ω*x, the arctangent simplifies to arctan(1)=pi/4 and the first term simplifies to (1/2)x*p= (1/2)nh(bar). However, I'm not sure where to go from here, or even positive if this is correct.

I know--or rather, think I know--that I'm supposed to set this integral equal to 2∏nh(bar) and solve for E.

However, the professor indicated we needed to find the endpoints where "the kinetic energy is zero." I know one of these points would be 0, but what's the other? Does it even matter here?

I'm really not seeing how I can get a result of E=nh(bar)ω. Even if I plug in E=nh(bar)ω into my indefinite integral I'm not coming up with the right answer.Please, any help is very greatly appreciated!EDIT: I have also realized that, since the integral is a closed loop, my integral should essentially be multiplied by 2 to account for the trip back.
 
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  • #2
So, I now have a result that looks like this:

(1/2)x*sqrt(2mE-m^2*ω^2*x^2) + (E*arctan((m*ω*x)/(sqrt(2mE-m^2*ω^2*x^2))))/ω = nh(bar)

I'm still not sure where to go from here, though.
 

FAQ: Using Generalization of Bohr Rule for 1D Harmonic Oscillator

What is the generalization of Bohr's rule for the 1D harmonic oscillator?

The generalization of Bohr's rule for the 1D harmonic oscillator is a mathematical principle that describes the energy levels of a quantum mechanical system, such as an atom or molecule, in terms of their vibrational motion. It is based on the observation that the energy levels of a harmonic oscillator are evenly spaced and can be described by a single parameter, the vibrational quantum number.

How is the generalization of Bohr's rule derived for the 1D harmonic oscillator?

The generalization of Bohr's rule for the 1D harmonic oscillator is derived using the Schrödinger equation, which is a fundamental equation in quantum mechanics that describes the time evolution of a quantum state. By solving the Schrödinger equation for the harmonic oscillator potential, the energy levels and corresponding wave functions can be obtained, leading to the generalization of Bohr's rule.

What is the significance of the generalization of Bohr's rule for the 1D harmonic oscillator?

The generalization of Bohr's rule for the 1D harmonic oscillator is significant because it provides a simple and elegant way to understand and describe the energy levels of a quantum mechanical system. It also allows for the prediction of experimental results and the calculation of various physical properties, making it a useful tool in theoretical and experimental research.

How does the generalization of Bohr's rule relate to other principles in quantum mechanics?

The generalization of Bohr's rule for the 1D harmonic oscillator is closely related to other principles in quantum mechanics, such as the uncertainty principle and the superposition principle. It also serves as a basis for more complex theories, such as the quantum theory of fields and the theory of quantum electrodynamics.

What are the practical applications of the generalization of Bohr's rule for the 1D harmonic oscillator?

The generalization of Bohr's rule for the 1D harmonic oscillator has numerous practical applications in various scientific fields, such as in spectroscopy, molecular dynamics, and quantum computing. It also has implications in technology, such as in the development of new materials and devices with unique quantum properties.

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