Time-independent wavefunction

In summary, the conversation discussed a problem involving a free particle of mass m moving in a one-dimensional space with a rigid wall at x=0. The person asked for help in finding a time-independent wavefunction that satisfies the given conditions, and also asked about the relationship between the wave vector k and energy E. The conversation also mentioned explicitly showing that the wavefunction found in part a) is an eigenfunction of the Hamiltonian for the system. Lastly, the person asked about the time-dependent state corresponding to the wavefunction and inquired about the progress made so far.
  • #1
danai_pa
29
0
I have a problems, help me please

a) A free particle of mass m moves in one-dimensional space in the interval 0 <= x, with energy E. There is a rigid wall at x = 0. Write down a time-independent wavefunction, which satisfies these conditions, in term of x and k wher k is the wave vector of the motion. State the relation between k and E for this wavefunction.


b) Show explicity that the wavefunction you have found in part a) is an eigenfunction of the Hamitonian for this system.

c) What is the time-dependent state, psi(x,t). corresponding to the wavefunction psi(x)?
 
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  • #2
It shouldn't be too complicated,what did you do so far?

Daniel.
 
  • #3


a) The time-independent wavefunction for a free particle in one-dimensional space with a rigid wall at x = 0 can be written as:

psi(x) = Ae^(ikx) + Be^(-ikx)

where A and B are constants and k is the wave vector of the motion. The relation between k and E for this wavefunction is given by:

E = (h^2 * k^2) / (2m)

where h is Planck's constant and m is the mass of the particle.

b) To show that this wavefunction is an eigenfunction of the Hamiltonian, we need to show that it satisfies the time-independent Schrodinger equation:

H * psi(x) = E * psi(x)

where H is the Hamiltonian operator. Substituting the wavefunction into this equation, we get:

H * (Ae^(ikx) + Be^(-ikx)) = (h^2 * k^2) / (2m) * (Ae^(ikx) + Be^(-ikx))

Expanding the Hamiltonian operator, we get:

(-h^2 / (2m)) * (d^2/dx^2) * (Ae^(ikx) + Be^(-ikx)) = (h^2 * k^2) / (2m) * (Ae^(ikx) + Be^(-ikx))

Simplifying, we get:

(-h^2 * k^2 / 2m) * (Ae^(ikx) + Be^(-ikx)) = (h^2 * k^2 / 2m) * (Ae^(ikx) + Be^(-ikx))

This shows that the wavefunction psi(x) is indeed an eigenfunction of the Hamiltonian, with eigenvalue E = (h^2 * k^2) / (2m).

c) The time-dependent state corresponding to the time-independent wavefunction psi(x) is given by:

psi(x,t) = Ae^(i(kx - Et)/h) + Be^(i(-kx - Et)/h)

where E is the energy and h is Planck's constant. This time-dependent state describes the probability amplitude of the particle at position x and time t.
 

1. What is a time-independent wavefunction?

A time-independent wavefunction is a mathematical representation of a quantum system in which the probability of finding a particle at a certain location does not change over time. It is a solution to the Schrödinger equation and is used to describe the energy states of a quantum system.

2. How does a time-independent wavefunction differ from a time-dependent wavefunction?

A time-independent wavefunction is a solution to the Schrödinger equation that does not change over time, while a time-dependent wavefunction describes the evolution of a quantum system over time. Time-independent wavefunctions are used to determine the energy states of a system, while time-dependent wavefunctions are used to calculate the probability of finding a particle at a certain location at a specific time.

3. What factors can affect a time-independent wavefunction?

The potential energy of a system, the shape of the potential energy function, and the boundary conditions of the system can all affect a time-independent wavefunction. Additionally, the mass and charge of the particle can also have an impact on the wavefunction.

4. How is a time-independent wavefunction used in quantum mechanics?

In quantum mechanics, the time-independent wavefunction is used to determine the energy levels and energy states of a quantum system. It is also used to calculate the probability of finding a particle at a certain location within the system.

5. Can a time-independent wavefunction change over time?

No, a time-independent wavefunction does not change over time. It is a static solution to the Schrödinger equation that describes the energy states of a quantum system. However, the probabilities of finding a particle at certain locations within the system can change over time as determined by the time-dependent wavefunction.

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