Double Delta Function Potential

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Discussion Overview

The discussion revolves around the analysis of a double delta function potential in quantum mechanics, specifically focusing on finding reflection (R) and transmission (T) coefficients. Participants explore the conditions for resonant transmission and the application of boundary conditions in solving the problem.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents the potential form and asks how to find R and T, as well as the conditions for resonant transmission.
  • Another participant suggests using a similar approach to solving a single delta function potential.
  • A third participant expresses having a solution for the single delta function potential but lacks understanding and seeks further assistance.
  • Discussion includes the assumption of plane waves for scattering states and the need to match boundary conditions at different regions.
  • A participant shares their derived general equations and boundary conditions, seeking validation of their correctness to proceed with calculations.

Areas of Agreement / Disagreement

There is no consensus on the correctness of the proposed solutions or the boundary conditions, as participants are seeking clarification and validation of their approaches. Multiple views on how to tackle the problem remain present.

Contextual Notes

Participants have not fully resolved the mathematical steps involved in applying boundary conditions or the implications of the potential's parameters. There may be assumptions regarding the incident wave direction and the nature of the delta function potential that are not explicitly stated.

Who May Find This Useful

Readers interested in quantum mechanics, particularly those studying scattering theory and delta function potentials, may find this discussion relevant.

jhosamelly
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I have

V (x) = [itex]\sqrt{((h-bar ^{2})V_{0})/2m}[/itex] [[itex]\delta(x-a)[/itex]+ [itex]\delta(x+a)[/itex]]

How do I find R and T?

Under what condition is there resonant transmission?
 
Last edited:
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How did you solve the 1 delta function potential? Do something similar here.
 
Matterwave said:
How did you solve the 1 delta function potential? Do something similar here.

well, Yes I have the solution for that but I don't understand it that much. Please help. Thanks
 
So, for the scattering states, you can assume plane waves. You can, for example, have an incident plane wave from the left, and then you can have waves going in both directions in the middle and on the right. And then you would need to match boundary conditions.
 
ok. I got these answers. Are these correct? Someone please tell me.

General Equations

[itex]U_{I}[/itex] = [itex]e^{ikx}[/itex] + R [itex]e^{-ikx}[/itex]


[itex]U_{II}[/itex] = A [itex]e^{ikx}[/itex] + B [itex]e^{-ikx}[/itex]


[itex]U_{III}[/itex] =T [itex]e^{-ikx}[/itex]


Boundary Conditions

if a = 0

[itex]U_{I}[/itex] = [itex]U_{II}[/itex]

1 + R = A + B

[itex]U_{II}[/itex] = [itex]U_{III}[/itex]

A + B = T



discontinuity equation

[itex]U'_{I}[/itex] - [itex]U'_{II}[/itex] = - [itex]\sqrt{\frac{2m V_{o}}{h-bar^{2}}}[/itex] [itex]U_{a}[/itex]

ik (1 - R) - ik (A - B) = - [itex]\sqrt{\frac{2m V_{o}}{h-bar^{2}}}[/itex] R


[itex]U'_{II}[/itex] - [itex]U'_{III}[/itex] = - [itex]\sqrt{\frac{2m V_{o}}{h-bar^{2}}}[/itex][itex]U_{a}[/itex]


ik (A-B) - ikT = - [itex]\sqrt{\frac{2m V_{o}}{h-bar^{2}}}[/itex] T


/// i hope someone can tell me if these are correct so I can continue my calculations. Thanks.
 

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