How Do Eigenfunctions and Eigenvalues Evolve in a 1-D Infinite Potential Well?

  • Thread starter Panic Attack
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This is because the wave function is normalized, meaning that the total probability of finding the particle at any point in the box at any time is equal to 1. In summary, the problem involves a 1-D box with two boundary conditions at x=0 and x=L, and the goal is to find the eigenfunctions and eigenvalues of the system. The wave function is given by φ(x,t) = (1/(3^1/2))U_2(x)e^(-iE_2t/h) + ((2/3)^1/2)U_3(x)e^(-iE_3t/h), and the probability density and total probability are given by φ(x,t)^2 and P(x,t),
  • #1
Panic Attack
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Homework Statement


I didn't put this in the right format the first time. My question is, I have a 1-D box confined at at x = 0 and x = L. So, points between 0 and L distances are the continuum state and otherwise distances be discontinous.
a) I need to find the egien functs: Un(x) and related egien values: En ... n are the excited levels represented as postive whole numbers.

The wave funct is: φ(x, t = 0) = (1/(3^1/2))U_2(x) + ((2/3)^1/2)U_3(x)


b) As time progresses, what will the function look like?
c) What is the prob. density (φ squared) and P(x,t) = total probability.


Homework Equations


Schrodinger Eq.


The Attempt at a Solution



What I have so far...

(-(h/2pi)^2)/2m * (d^2/dx^2)Psi(x) = E*Psi(x)
Psi(x)|x=0 = Asin(0) + Bcos(0) = B = 0 ?
Psi(x)|x=L = Asin(kL) + Bcos(kL) = 0 ?

[0 0; sin(kL) cos(kL)] *[A;B] = [0 0]

set KnL/2 = n*pi
En = (h/2pi)^2 *k^2]/2m
= [(h/2pi)^2] /2m * (2n*pi/L)
 
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  • #2
^2= [h^2/8mL^2]*n^2Un(x) = A_n sin[K_n(x-L/2)] + B_n cos[k_n(x-L/2)] A_n = sqrt(2/L)B_n = 0b) As time progresses, what will the function look like?The wave function will have the same form as before, but with time-dependent coefficients:φ(x,t) = (1/(3^1/2)U_2(x))e^(-iE_2t/h) + (2/3^1/2)U_3(x)e^(-iE_3t/h) c) What is the prob. density (φ squared) and P(x,t) = total probability.The probability density is given by φ(x,t)^2:φ(x,t)^2 = (1/3)*U_2(x)^2e^(-2iE_2t/h) + (4/9)*U_3(x)^2e^(-2iE_3t/h) + (2/3)*U_2(x)*U_3(x)e^(-i(E_2+E_3)t/h) The total probability is given by P(x,t):P(x,t) = ∫φ(x,t)^2dx = ∫(1/3)*U_2(x)^2e^(-2iE_2t/h) + (4/9)*U_3(x)^2e^(-2iE_3t/h) + (2/3)*U_2(x)*U_3(x)e^(-i(E_2+E_3)t/h)dx = 1
 

FAQ: How Do Eigenfunctions and Eigenvalues Evolve in a 1-D Infinite Potential Well?

What is a 1-D infinite potential well?

A 1-D infinite potential well is a model used in quantum mechanics to represent a particle confined to a one-dimensional space. It consists of an infinitely high potential barrier at the boundaries, creating a well or box where the particle can move within.

How does a particle behave in a 1-D infinite potential well?

In a 1-D infinite potential well, a particle can only exist within the boundaries of the well. It behaves as a standing wave, with discrete energy levels and probabilities of being found at different positions within the well. The particle also experiences reflections at the boundaries, leading to interference patterns.

What is the significance of the 1-D infinite potential well?

The 1-D infinite potential well is a simple yet powerful model that helps us understand the behavior of particles in confined spaces. It also serves as an important example in quantum mechanics and is often used to illustrate concepts such as wave functions, energy quantization, and boundary conditions.

How is the energy of a particle in a 1-D infinite potential well determined?

The energy of a particle in a 1-D infinite potential well is determined by the Schrödinger equation. The solutions to this equation give the allowed energy levels of the particle, which are quantized and depend on the size of the well. The lowest energy level is known as the ground state.

Can a particle escape from a 1-D infinite potential well?

No, a particle cannot escape from a 1-D infinite potential well as the potential barrier at the boundaries is infinitely high. However, it is possible for the particle to tunnel through the barrier, which is a quantum mechanical phenomenon where the particle has a non-zero probability of being found outside the well.

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