Double Delta Function Potential

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The discussion focuses on solving the double delta function potential given by V(x) = √((ħ²V₀)/2m) [δ(x-a) + δ(x+a)]. Participants seek to determine reflection (R) and transmission (T) coefficients, and the conditions for resonant transmission. The approach involves using plane wave scattering states and matching boundary conditions at the delta function potentials. Key equations for incident, transmitted, and reflected waves are presented, along with boundary conditions that must be satisfied. Clarification is requested on the correctness of the derived equations to proceed with further calculations.
jhosamelly
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I have

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

How do I find R and T?

Under what condition is there resonant transmission?
 
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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

U_{I} = e^{ikx} + R e^{-ikx}


U_{II} = A e^{ikx} + B e^{-ikx}


U_{III} =T e^{-ikx}


Boundary Conditions

if a = 0

U_{I} = U_{II}

1 + R = A + B

U_{II} = U_{III}

A + B = T



discontinuity equation

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

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


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


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


/// i hope someone can tell me if these are correct so I can continue my calculations. Thanks.
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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