Solving the Schrodinger Equation for 1D Electron Motion

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Discussion Overview

The discussion focuses on solving the Schrödinger equation for the one-dimensional motion of an electron in the absence of forces. Participants explore the appropriate form of the equation, the implications of setting the potential energy to zero, and the nature of the energy spectrum in this context.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant questions whether to use the time-independent form of the Schrödinger equation and suggests setting the potential V(x) to zero.
  • Another participant confirms the use of the time-independent form and the zero potential, indicating that any value of energy E leads to an acceptable solution due to the lack of boundary conditions.
  • It is noted that the energy spectrum for a free particle can take any real positive value, leading to a continuous spectrum.
  • A later reply introduces the necessity of boundary conditions, arguing that solutions must go to zero at infinity for normalizability, which complicates the treatment of free particles.
  • Participants discuss the implications of non-normalizable wavefunctions and suggest that wavepackets should be used in cases where V(x) = 0.

Areas of Agreement / Disagreement

Participants generally agree on the use of the time-independent Schrödinger equation and the implications of setting V(x) to zero. However, there is disagreement regarding the treatment of boundary conditions and the normalizability of solutions, indicating that the discussion remains unresolved on these points.

Contextual Notes

Limitations include the dependence on boundary conditions for normalizability, which are not clearly defined in the case of a free particle. The discussion also highlights the challenges associated with non-normalizable wavefunctions.

irony of truth
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I am trying to find the Schrödinger's equation for the one-dimensional motion of an electron, not acted upon by any forces.

So.. should I begin using the time independent form of the Schrödinger's equation? What should I arrive at? Should I let my V(x) = 0?

Also, how do I show that the total energy of that particular Schrödinger's equation is not quantized?
 
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What's the general form of the SE's equation...?What's the free particle's Hamiltonian...?

Daniel.
 
irony of truth said:
So.. should I begin using the time independent form of the Schrödinger's equation?

Yes.

Should I let my V(x) = 0?

Yes.

Also, how do I show that the total energy of that particular Schrödinger's equation is not quantized?

Find the general solution of your Schrödinger equation, and show that any value of E leads to an acceptable solution for your boundary conditions. Of course, you don't really have any boundary conditions, which simplifies matters! (unlike the infinite square well a.k.a. "particle in a box" where the boundary conditions restrict the acceptable values of E to a discrete set)
 
Thank you for your helps... I can manage from here... E = (hbar)k^2 / (2m) >= 0
 
That's right.And the "k" wan take any real value...Making the energy spectrum the real positive semiaxis.

Daniel.
 
jtbell said:
Of course, you don't really have any boundary conditions
You do have boundary conditions, you have to require that your solution goes to zero at infinity, otherwise your solution is not normalizable.
For a free particle, that actually represents a big problem, since the free particle wavefunction ([tex]e^{ipx/\hbar[/tex]) isn't nomalizable!
That's the reason one should really work with wavepackets in the cases where [tex]V(x) = 0[/tex], those are normalizable.
Almost any textbook in quantum mechanics has a discussion on that particular topic.
 
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