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Commit 04a85057 authored by Michael Wimmer's avatar Michael Wimmer
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fix Schroedinger

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1 merge request!9DifferentialEquationsLecture2
...@@ -240,13 +240,13 @@ is a $3$-rd order equation because of the third derivative with respect to x ...@@ -240,13 +240,13 @@ is a $3$-rd order equation because of the third derivative with respect to x
in the equation. in the equation.
To begin, we demonstrate that PDE's are of fundamental importance in physics, To begin, we demonstrate that PDE's are of fundamental importance in physics,
especially in quantum physics. In particular, the Schr\"{o}dinger equation, especially in quantum physics. In particular, the Schrödinger equation,
which is of central importance in quantum physics is a partial differential which is of central importance in quantum physics is a partial differential
equation with respect to time and space. This equation is very important equation with respect to time and space. This equation is very important
because it describes the evolution in time and space of the entire description because it describes the evolution in time and space of the entire description
of a quantum system $\psi(x,t)$, which is known as the wavefunction. of a quantum system $\psi(x,t)$, which is known as the wavefunction.
For a free particle in one dimension, the Schr\"{o}dinger equation is For a free particle in one dimension, the Schrödinger equation is
$$i \hbar \frac{\partial \psi(x,t)}{\partial t} = - \frac{\hbar^2}{2m} \frac{\partial^2 \psi(x,t)}{\partial x^2}. $$ $$i \hbar \frac{\partial \psi(x,t)}{\partial t} = - \frac{\hbar^2}{2m} \frac{\partial^2 \psi(x,t)}{\partial x^2}. $$
...@@ -259,7 +259,7 @@ the equation. In partial differential equations at least one such constant will ...@@ -259,7 +259,7 @@ the equation. In partial differential equations at least one such constant will
arise from the time derivative and likewise at least one from the spatial arise from the time derivative and likewise at least one from the spatial
derivative. derivative.
For the Schr\"{o}dinger equation, we could supply the initial conditions For the Schrödinger equation, we could supply the initial conditions
$$\psi(x,0)= \psi_{0}(x) \ & \ \psi(0,t) = \psi{t, L} = 0.$$ $$\psi(x,0)= \psi_{0}(x) \ & \ \psi(0,t) = \psi{t, L} = 0.$$
...@@ -287,7 +287,7 @@ physics. ...@@ -287,7 +287,7 @@ physics.
## Separation of variables ## ## Separation of variables ##
Let us focus on the one dimensional Schr\"{o}dinger equation of a free particle Let us focus on the one dimensional Schrödinger equation of a free particle
$$i \hbar \frac{\partial \psi(x,t)}{\partial t} = - \frac{\hbar^2}{2m} \frac{\partial^2 \psi(x,t)}{\partial x^2}. $$ $$i \hbar \frac{\partial \psi(x,t)}{\partial t} = - \frac{\hbar^2}{2m} \frac{\partial^2 \psi(x,t)}{\partial x^2}. $$
...@@ -336,7 +336,7 @@ needed to introduce a separation constant, which remains to be determined. ...@@ -336,7 +336,7 @@ needed to introduce a separation constant, which remains to be determined.
### Boundary and eigenvalue problems ### ### Boundary and eigenvalue problems ###
Continuing on with the Schr\"{o}dinger equation example from the previous Continuing on with the Schrödinger equation example from the previous
section, let us focus on section, let us focus on
$$-\frac{\hbar^2}{2m} \phi''(x) = \lambda \phi(x),$$ $$-\frac{\hbar^2}{2m} \phi''(x) = \lambda \phi(x),$$
...@@ -477,7 +477,7 @@ the eigenfunctions of $L$. ...@@ -477,7 +477,7 @@ the eigenfunctions of $L$.
In terms of hermitian operators and their eigenfunctions, the eigenfunctions In terms of hermitian operators and their eigenfunctions, the eigenfunctions
play the role of the orthonormal basis. In reference to our running example, play the role of the orthonormal basis. In reference to our running example,
the 1D Schr\"{o}dinger equation of a free particle, the eigenfunctions the 1D Schrödinger equation of a free particle, the eigenfunctions
$sin(\frac{n \pi x}{L})$ play the role of the basis functions $\ket{u_n}$. $sin(\frac{n \pi x}{L})$ play the role of the basis functions $\ket{u_n}$.
To close our running example, consider the initial condition To close our running example, consider the initial condition
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