diff --git a/src/article/main.md b/src/article/main.md index 05446b9..5f380e9 100644 --- a/src/article/main.md +++ b/src/article/main.md @@ -1,9 +1,51 @@ # The schrodinger equation -## Mathematical prerequisites +## Preface -To understand this article, you will need a thorough understanding of complex numbers. +This article will cover the schrodinger equation, which represents a non-relativistic differential equation governing +quantum particles. Relativistic effects are not taken into account here. -I will also use Euler's formula $e^{i*x} = \cos(x) + i*\sin(x)$ +## Deriviation -$$e^{ix} = \cos(x) + i*\sin(x)$$ +It should be mentioned that the schrodinger equation cannot be derived traditionally but rather represents a +semi-logical conclusion from a number of assumptions/axioms. + +### Known properties of traditional waves + +In quantum mechanics, particles are assumed to be governed by a wave function. [Louis- +de-Broglie](https://de.wikipedia.org/wiki/Louis_de_Broglie) postulated that matter waves should have the same wavelength +as photons, whose wavelength depends on their respective impulse: + +$$\lambda = \frac{h}{p} = \frac{h}{m*v} $$ + +A basic wave function for a travelling monochromatic wave can be written as: + +$$ \Psi = \cos(k*x - \omega * t) = e^{i*(k*x - \omega * t)} $$ + +Schrodinger assumed that a matter wave should have the same wave form. From this, we can derive $k = +\frac{2*\pi}{\lambda} = \frac{2 * \pi * p}{h} $, using the de-Broglie-wavelength as mentioned above. With $ v = f * +\lambda $ for each wave, one can also conclude that $\omega = 2 * \pi * f = 2 * \pi * \frac{v}{\lambda} = \frac{2 * \pi +* v * p}{h} $. We can rewrite the wave function as follows: + +$$ \Psi = e^{i*(\frac{2 * \pi * p}{h}*x - \frac{2 * \pi * v * p}{h} * t)} = e^{\frac{i*p}{\hbar}*(x - v*t)} $$ + +### Obtaining the Schrodinger equation through energy conversion + +The total sum of energy should be a constant for physical particles. For this, +the sum of the kinetic Energy $E_{kin} = \frac{p^{2}}{2*m}$ and potential energy $E_{pot} = V$, where V describes some +arbitrary potential, which in practice will need to be multiplied by its respective "charge" of a particle (this could +be its mass for a gravitational potential or the charge for electric fields) needs to stay constant. Thusly, one can +write: + +$$ E = E_{kin} + E_{pot} = \frac{p^{2}}{2*m} + V $$ +$$ \hat{E} * \Psi = \frac{\hat{p}^{2}}{2*m} * \Psi + V * \Psi $$ + +$\hat{E}$ and $\hat{p}$ are some (yet unknown) operators on $\Psi$ which respectively should return the impulse and +total energy for the wave function. For wave function to be valid, this equation must be true. On the other hand, we can +obtain these operators using the basic wave function mentioned above. + +Noting the factor $p$ in the exponent of $\Psi$, you might write $\frac{\partial{\Psi}}{\partial{x}} = \frac{i * +p}{\hbar}$ and obtain $p = -i*\hbar*\frac{\partial{\Psi}}{\partial{x}}$. Plugging this back into the energy conservation +equation, we obtain the time-independent schrodinger equation: + +$$ \hat{E} * \Psi = -\frac{\hbar^2}{2*m} * \frac{\partial^2 \Psi}{\partial^2 x} + V*\Psi$$