# A How to solve this DE?

1. Dec 29, 2016

### OneByBane

I am currently trying to solve this differential equation:

r2/F(r) d2F(r)/dr2 + 2mr2/h2(E + Zt2/kr) - a2 = 0

Wher m, h, E, Z, t and k are other variables and 'a' can have values 1, 2, 3, 4..... (Whole numbers)

I have come across this while solving a problem in physics and have no clue if this even has a solution.
Any help will be appreciated greatly.

2. Dec 29, 2016

### Strum

If your equation is given by ( please please please learn to tex )
$$\frac{r^2}{f(r)} \frac{d^2 f(r)}{dr^2} + \frac{2mr^2}{h^2}\left(E + \frac{zt^2}{kr}\right) -a^2 = 0$$
Then you can rewrite to
$$\left( \frac{d^2}{dr^2} + \frac{2mE}{h^2} + \frac{2mzt^2}{h^2 kr} - \frac{a^2}{r^2} \right) f(r) = 0$$
Which is pretty close to the Whittaker equation ( https://en.wikipedia.org/wiki/Whittaker_function ).

3. Dec 29, 2016

### Ssnow

This is a second order differential equation, you can rewrite it as:

$\frac{d^2}{dr^2}F(r)+ \left[\frac{2m}{h^2}\left(E-\frac{h^2a^2}{2mr^2} + \frac{Zt^2}{kr}\right)\right]F(r) =0$

calling $a(r)=\frac{2m}{h^2}\left(E-\frac{h^2a^2}{2mr^2} + \frac{Zt^2}{kr}\right)$ we have that

$\frac{d^2}{dr^2}F(r)+ a(r)\cdot F(r) =0$

to solve this DE you must find a particular solution in order to find the general ...

4. Jan 4, 2017

### the_wolfman

The solutions to this equation are called Coulomb wave functions. You can also write the solution in terms of confluent hypergeometric functions.