- #1
gomboc
- 39
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I'm looking to find solutions for K to the following equation which arises in the Kronig-Penney model of a periodic potential:
[tex] \frac{P}{Ka}\sin(Ka) + \cos(Ka) = -1 [/tex]
The equation is such that for a given value of P, there will be a range of K values having a real solution, and a range of K values having no real solution. The idea is to find the boundaries of these ranges. (knowing of course that the trivial solution of K = pi/a is one of them, I'm looking for the other).
I can't think of a good way to do this analytically. If I expand the trig functions into series, I can find the maximum value that can be added to K and still give a solution, but that is not an exact method.
Any ideas would be much appreciated.
[tex] \frac{P}{Ka}\sin(Ka) + \cos(Ka) = -1 [/tex]
The equation is such that for a given value of P, there will be a range of K values having a real solution, and a range of K values having no real solution. The idea is to find the boundaries of these ranges. (knowing of course that the trivial solution of K = pi/a is one of them, I'm looking for the other).
I can't think of a good way to do this analytically. If I expand the trig functions into series, I can find the maximum value that can be added to K and still give a solution, but that is not an exact method.
Any ideas would be much appreciated.