Show that a wave function is correctly normalised?

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Discussion Overview

The discussion revolves around the normalization of wave functions in quantum mechanics, specifically how to demonstrate that a wave function is correctly normalized. Participants explore the mathematical requirements for normalization and the implications of expectation values for position and momentum.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Homework-related

Main Points Raised

  • One participant inquires about the necessity of the complex conjugate when integrating the square of the wave function for normalization.
  • Another participant clarifies that the absolute square of the wave function, which involves multiplying the wave function by its complex conjugate, is required for normalization.
  • A participant questions whether the expectation value of position can be zero, leading to a discussion about the conditions under which this is possible.
  • It is noted that for a hydrogen atom in the ground state, the expectation value of position can indeed be zero, while for a particle in an infinite square well, it cannot be.
  • The participant expresses uncertainty about the conditions of a specific problem and considers checking their work regarding the expectation values.
  • There is a follow-up question about whether the expectation value of momentum can also be zero if the expectation value of position is zero.

Areas of Agreement / Disagreement

Participants generally agree on the method for normalizing a wave function, but there are differing views on the implications of expectation values, particularly regarding their conditions and possible values.

Contextual Notes

The discussion highlights the dependence on specific conditions and definitions related to wave functions and expectation values, which are not fully specified in the context of the questions raised.

Dream_Theater
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Hi, could someone please tell me how I would show that a wave function is correctly normalised?

I know to integrate the square of the function between infinity and negative infinity, but is the complex conjugate required?

Any help is much appreciated :D
 
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You integrate the absolute square of the wave function, which is the wave function times its complex conjugate.
 
Thanks, that helps a lot. I can see where I was going wrong.

Also, for a wavefunction, can the expectation value of the position be equal to zero?
 
It means that the particle is equally likely to be found on one side of the origin of your coordinate system, as on the opposite side. Whether that's possible or not depends on the situation. For a hydrogen atom in the ground state, with the proton at the origin, <x> for the electron is in fact zero. For the classic textbook particle in an "infinite square well" whose boundaries are at x = 0 and x = L, <x>= 0 is not possible.
 
Thanks, that really helps. I was wondering because I was looking at a question that didn't really specify the conditions. I'll check through my working and see if I've made any mistakes. Also, if <x> is zero, can <p> also be zero?
 

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