Question about time-variant Schrodinger's eq'n

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Discussion Overview

The discussion revolves around the time-variant form of Schrödinger's equation, specifically focusing on the treatment of complex numbers within the equation and the interpretation of the energy term (E). Participants explore the implications of using complex arithmetic in programming contexts and seek clarification on the physical meaning of E in relation to energy concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether a complex number of the form c=a+bi can be used in the time-variant Schrödinger's equation, considering the representation of i as sqrt(-1).
  • Another participant suggests that complex arithmetic must be used throughout when dealing with complex numbers in the equation.
  • A participant expresses uncertainty about the interpretation of the energy term E, asking if it represents total system energy, kinetic energy, or mass-energy equivalence.
  • There is a discussion about the relationship between E and the Hamiltonian, with one participant asserting that E is a scalar representing one of the eigenenergies of the system.
  • Another participant proposes a hypothetical value for E based on the relation E=h/wavelength, relating it to a wave function for a beam of light.
  • Concerns are raised about the applicability of the Hamiltonian in describing a beam of light, with a suggestion that quantum electrodynamics may be necessary for a complete understanding.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the energy term E and its relationship to the Hamiltonian. There is no consensus on how to approach the complexities of using Schrödinger's equation in programming or the physical implications of the energy term.

Contextual Notes

Participants note that the discussion involves a mix of classical and quantum interpretations, with some confusion regarding the application of the Hamiltonian and the nature of energy in the context of the Schrödinger equation.

woody stanford
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The question I have is regarding the time-variant form of Schrödinger's equation. Can I just put a complex number of form c=a+bi where the i is in it or can I just literally put sqrt(-1) where the i is:

schrod_tv_eqn1.png


addendum: sorry forgot the t in the right-hand term, it should read (r,t) instead of (r)

Also any comments/insights on some of the other terms in it would be welcomed (as I'm writting a c program to inject various values into it) and would appreciate the help.

Was thinking if I could just put a+bi in there that to put it back to i all I would have to do is set (real)a=0 and (imaginary)b=1
 
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woody stanford said:
The question I have is regarding the time-variant form of Schrödinger's equation. Can I just put a complex number of form c=a+bi where the i is in it or can I just literally put sqrt(-1) where the i is:

View attachment 119009

addendum: sorry forgot the t in the right-hand term, it should read (r,t) instead of (r)

Also any comments/insights on some of the other terms in it would be welcomed (as I'm writting a c program to inject various values into it) and would appreciate the help.

Was thinking if I could just put a+bi in there that to put it back to i all I would have to do is set (real)a=0 and (imaginary)b=1

I think you are going to have to treat it as a complex number and make sure you use complex arithmetic throughout.
 
mike1000 said:
I think you are going to have to treat it as a complex number and make sure you use complex arithmetic throughout.

See that's why I come here...get a few opinions...a few facts...a few points of view. Thank you sir. Basically what I was thinking but wanted to bounce it off the ole colleagues. Means I'm not nuts (comforting to know). lol
 
OK, got some more question.

Still working on my program to compute the time invariant version of SE. Here is that equation:

schrod_ti_eqn1.png


Ok, here is my question. The E here I believe can have a Hameltonian substituted in BUT I'm interested in the classic interpretation of the E term here. Is it system total energy? I assume it has a local associated with it, but what "energy" does it represent?

Is it the mass terms converted to energy via the equation e=mc^2? Is it the total kinetic energy of all particles within the local system being described? What exactly does that E term mean?

...(and don't reference a Hameltonian unless it gets me closer to what I'm looking for...in other words if you invoke the Hameltonian option you will be required lol to explain it from there, not from the easier to explain E at that point)?

Addendum: ok, came up with a hypothetical E value based on the relation E=h/wavelength since I'm using a psi(x)=A*sin(kx+d) wave function that I believe is for [the electrical component for] a beam of light (ie. photon). I'm using a 500 nm (visible red) beam of light in the simulation btw (if it helps).

E=h/wavelength
 
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woody stanford said:
Still working on my program to compute the time invariant version of SE. Here is that equation:
Always good to learn the language: they are called the time-dependent and time-independent Schrödinger equation.

woody stanford said:
Ok, here is my question. The E here I believe can have a Hameltonian substituted in BUT I'm interested in the classic interpretation of the E term here. Is it system total energy? I assume it has a local associated with it, but what "energy" does it represent?
There is a lot of confusion here. You can't "substitute" E for a Hamiltonian, since you have the Hamiltonian on the left-hand side. E is a scalar, and it is indeed the energy of the system. To be more precise, it is one of the eigenenergies. (You do know what an eigenvalue problem is?) Also, you don't need to invoke a "classical interpretation" for E.

woody stanford said:
Is it the mass terms converted to energy via the equation e=mc^2? Is it the total kinetic energy of all particles within the local system being described? What exactly does that E term mean?
This is purely non-relativistic, so there is no ##mc^2## term. To know what the energy corresponds to, you have to look at the Hamiltonian. In your case, the first term is the kinetic energy, while the second is an unspecified potential ##V(x)##. So the total energy is kinetic + potential energy, with the potential energy correspond to whatever lead to the presence of a position dependent potential ##V(x)## is the first place.

woody stanford said:
Addendum: ok, came up with a hypothetical E value based on the relation E=h/wavelength since I'm using a psi(x)=A*sin(kx+d) wave function that I believe is for [the electrical component for] a beam of light (ie. photon). I'm using a 500 nm (visible red) beam of light in the simulation btw (if it helps).

E=h/wavelength
You can't use that Hamiltonian to describe a beam of light. This is only for a massive particle. And if you want to talk about photons, you'll have to upgrade to quantum electrodynamics, which I guess is not what you want to do here.
 

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