Question about a barrier potential E<V

In summary, the conversation discusses finding the transmitted coefficient and reflected coefficient for a case where the barrier potential is less than the energy of the particle. The homework equations for these coefficients are given, as well as the wavefunctions for the incident, reflected, and transmitted waves. The solution for this case can be found on Wikipedia, but the question asks about the case between two different wavefunctions. The solution is checked using the probability current equation, and it is found that the incident and reflected waves have a value of zero while the transmitted wave has a complex value. The equation for the coefficients results in dividing by zero, which requires further clarification. It is suggested to check the wavefunctions for the step function potential.
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Homework Statement


Question_________________________________________________________________________________
Find transmitted coefficient and reflected coefficient in case barrier potential E<V ?
determine.
##Ψ_{I} = Ae^{ikx}+Be^{-ikx}##
##Ψ_{II} = De^{βx}+Ee^{-βx}##
##Ψ_{III} = Ce^{ikx}##

Homework Equations


___________________________________________________________________________________________
##R = |\frac{J_{ref}}{J_{inc}}|##
##T = |\frac{J_{tran}}{J_{inc}}|##
and J is Probability current (https://en.wikipedia.org/wiki/Probability_current)
__________________________________________________________________

For transmitted coefficient and reflected coefficient between ##Ψ_{I}## and ##Ψ_{III}##
where
incident wave = ## Ae^{ikx} ##
reflect wave = ## Be^{-ikx} ##
transmit wave = ## Ce^{ikx} ##
I can find a solution for this case.
https://en.wikipedia.org/wiki/Rectangular_potential_barrier#E_<_V0 << Here is the answer.
___________________________________________________________________________________________

The Attempt at a Solution


But my question is asked in the case transmitted coefficient and reflected coefficient between ##Ψ_{II}## and ##Ψ_{III}##.
I know
incident wave = ## De^{βx} ##
reflect wave = ## Ee^{-βx} ##
transmit wave = ## Ce^{ikx} ##

I checked it
##J = \frac{ħ}{2mi}(Ψ^* \frac{dΨ}{dx}-Ψ\frac{dΨ^*}{dx})##
I seen that incident wave and reflect wave are real function.
So ##J_{inc}=0## and ##J_{ref}=0##
Because ##Ψ^* \frac{dΨ}{dx}-Ψ\frac{dΨ^*}{dx}=Ψ\frac{dΨ}{dx}-Ψ\frac{dΨ}{dx}=0##
But transmit wave is complex function.
So ##J_{tran}=\frac{ħk}{m}|C|^2##
From Eq.
##R = |\frac{J_{ref}}{J_{inc}}|##
##T = |\frac{J_{tran}}{J_{inc}}|##
in this case ##R = \frac{0}{0}## and ##T = \frac{ \frac{ħk}{m}|C|^2}{0}##
what does mean?
##R = \frac{0}{0}## and ##T = \frac{ \frac{ħk}{m}|C|^2}{0}##
Or i miss something ? please re check my solution
 

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  • #2
Check out the wavefunctions for the step function potential
(you can always add solutions to the homogeneous equation - as long as they sum up to zero)
 
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