What are the normalizations constants of psi(x) in a finite potential box?

In summary, there is no closed form solution for the normalizations constants of psi(x) in a finite potential box. The even parity solutions are of the form A cos(kx) for |x|<a and B exp(-k|x|) for |x|>a, with the energy eigenvalue being E=hbar^2 k^2/2m. The eigenvalue condition and the ratio of B/A can be solved graphically or numerically, but not analytically. The value of A can then be obtained by normalizing psi(x). The best way to solve this computationally is to use graphical or numerical methods to determine the energy eigenvalue and then use it to solve for the normalization constant.
  • #1
j-lee00
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What are the normalizations constants of psi(x) in a finite potential box?

is there an algebraic or analytical solution.

I have the solution to the infinite box but it seems the two cases are not comparable. As in the finite box the particle does not need to be in the box?
 
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  • #2
There's no closed form solution. Let's set [itex]V(x)=0[/itex] for [itex]-a<x<a[/itex] and [itex]V(x)=\hbar^2 \gamma^2/2m[/itex], where [itex]\gamma[/itex] is a constant, for [itex]|x|>a[/itex]. Then, even parity solutions are of the form [itex]\psi(x)=A\cos(kx)[/itex] for [itex]|x|<a[/itex] and [itex]B\exp(-\kappa|x|)[/itex] for [itex]|x|>a[/itex], where [itex]k^2+\kappa^2=\gamma^2[/itex], and the energy eigenvalue is [itex]E=\hbar^2 k^2/2m[/itex]. Matching [itex]\psi(x)[/itex] and [itex]\psi'(x)[/itex] at [itex]x=a[/itex] yields the eigenvalue condition [itex]\kappa=k\tan(ka)[/itex] (which must be satisfied together with [itex]k^2+\kappa^2=\gamma^2[/itex]; this pair of equations can be solved graphically or numerically, but not analytically) and [itex]B/A = \exp(\kappa a)\cos(ka)[/itex]. You can then get the value of [itex]A[/itex] by normalizing [itex]\psi(x)[/itex], which will give you some expression in terms of [itex]k[/itex], [itex]\kappa[/itex], and [itex]a[/itex], with [itex]k[/itex] and [itex]\kappa[/itex] being fixed by the energy eigenvalue (which can only be determined graphically or numerically).
 
  • #3
what is the best way to solve it computationally?
 

1. What is the definition of normalization constant in a finite potential box?

The normalization constant in a finite potential box refers to a constant value that is used to scale the wave function of a particle in a confined space so that the total probability of finding the particle within that space is equal to one.

2. Why do we need to calculate normalization constants in a finite potential box?

Calculating normalization constants in a finite potential box is necessary in order to ensure that the wave function of a particle is properly scaled and represents a physically meaningful probability distribution. It also allows for the calculation of other important quantities such as the expectation value and variance of the particle's position.

3. How do we calculate the normalization constant in a finite potential box?

The normalization constant in a finite potential box can be calculated by integrating the square of the wave function over the entire finite potential box and then taking the square root of the result. This ensures that the total probability of finding the particle within the box is equal to one.

4. Can the normalization constant in a finite potential box be negative?

No, the normalization constant in a finite potential box cannot be negative. It represents a scaling factor for the wave function, and the square of the wave function must always be a positive value in order to represent a physically meaningful probability distribution.

5. How do normalization constants in a finite potential box differ from those in an infinite potential well?

In an infinite potential well, the normalization constant is a constant value that is independent of the energy level of the particle. However, in a finite potential box, the normalization constant varies depending on the energy level of the particle and must be calculated separately for each energy level.

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