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One-dimensional scattering at a potential barrier of any shape

Posted 10 years ago

I am trying to solve the problem of electron reflection at a finite potential barrier of a given functional shape (to be used as a parametrized input) in one dimension. My aim is to determine the reflection phase shift as a function of the electron energy. I am looking for a notebook to start with, and then conveniently manipulate the function parameters.

POSTED BY: Enrique Ortega
3 Replies
Posted 10 years ago
POSTED BY: Enrique Ortega

Are you aware of the fact that you can simulate what happens if you let run an arbitrary wave function towards an arbitrarily formed potential barrier by making use of the time-dependent Schroedinger equation in a suitable discretized form? This works even for the relativistic electron as described by Dirac's equation. Among my contributions to Wolfram Demonstrations there are two examples of that. One only non-relativistic, and one which treates the non-relativistic and the lelativistic case in parallel. By having available dynamics of arbitrary states governed by arbitrary Hamiltonians (in 1D, though) we don't have to restrict ourselves to the specialized situations treated in the QM textbooks with the aim of working out analytic solutions. Using Mathematica simply as a means to implement the formulas generated in those textbooks for special cases does not exhaust the power of Mathematica.

POSTED BY: Ulrich Mutze

You can't solve the problem without specifying the functional form of V[x]. The Schrödinger equation is

1/2 \[Psi]''[x] + V[x] \[Psi][x] = k^2/2 \[Psi][x]

with a scattering solution of the form

\[Psi][x] = E^(I k x) + r[k, x] E^(-I k x) + t[k, x] E^(I k x)

Given V[x], you can separate the real and imaginary parts to the equation using ComplexExpand[ ], you get two rather complicated equations which determine r[k,x] and t[k,x].

POSTED BY: S M Blinder
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