Exponentials or trig functions for finite square well?

In summary, both exponentials and trig functions can be used to solve for the wave function in a finite square well. There is no specific way to determine which method will make the problem easier, but for infinite square wells, using sines can be convenient to satisfy boundary conditions. For transmission and reflection coefficients, exponentials may be slightly easier to work with. However, both methods are equivalent and it ultimately depends on personal preference.
  • #1
baouba
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How do you know when to use exponentials and trig functions when solving for the wave function in a finite square well? I know you can do both, but is there some way to tell before hand which method will make the problem easier? Does it have something to do with parity?
 
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  • #2
baouba said:
How do you know when to use exponentials and trig functions when solving for the wave function in a finite square well? I know you can do both, but is there some way to tell before hand which method will make the problem easier? Does it have something to do with parity?

The two approaches are equivalent. The point of using sines and cosines is to get a complete basis that is either even or odd under the transformation [itex]x \Rightarrow -x[/itex]. But it really doesn't make much difference.

For infinite square wells, using sines is convenient because you can easily make the wave function zero at the two boundary points by choosing a basis function of the form [itex]sin(kx)[/itex] where [itex]k = \frac{n \pi}{L}[/itex].
 
  • #3
From my experience, exponentials seem to be a little easier especially when finding transmission and reflection coefficients (but as steven daryl said: they are completely equivelant)
 

1. What is a finite square well in terms of exponentials and trig functions?

A finite square well is a potential energy function that has a finite depth and extends for a finite distance. It is often used to model quantum systems, such as electrons in an atom, and can be described using both exponentials and trigonometric functions.

2. How are exponentials and trig functions used to solve for the energy levels of a finite square well?

Exponentials and trig functions are used in the Schrödinger equation to solve for the energy levels of a finite square well. The solutions to the equation are in the form of sinusoidal functions, which can be described using both exponentials and trigonometric functions.

3. What is the difference between the solutions for even and odd energy levels in a finite square well?

The solutions for even energy levels in a finite square well are described using cosine functions, while the solutions for odd energy levels are described using sine functions. This is because the even solutions have a symmetric wavefunction, while the odd solutions have an anti-symmetric wavefunction.

4. Can the solutions for a finite square well be used to describe other systems?

Yes, the solutions for a finite square well can be used to describe other systems with similar potential energy functions. For example, a particle in a box or a harmonic oscillator can also be described using the same mathematical equations and solutions.

5. How does the depth and width of a finite square well affect the energy levels?

The depth and width of a finite square well affect the energy levels by changing the potential energy function and thus altering the solutions to the Schrödinger equation. A deeper well will have lower energy levels, while a wider well will have more energy levels and a smaller spacing between them.

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