I started working with molecular modelling and stuck at the following problem.
I need to calculate dihedral interaction energy by hand. The simplest form of the equation is $V = \frac{Va}{2} * \left( 1 + \cos{\left( n \phi - \phi_0 \right)} \right )$. This refers to the energy term. In the real world there may be more than one terms - one, two etc...
From experiment I have plot of dependency $V$ on $\phi$, where is $\phi$ belongs to the $\left[ 0; 2\pi \right]$ interval and increases by some value (in my case $d\phi = 5$ so I have $72$ points). By visual analysis I can conclude that I have more than one energy term, because final plot is the sum of different cosines. So I want to do FFT on the $V$ data. But as soon as i know FFT applies only to the functions which are determined on the time-domain but not angle-domain...
So my question is: how to conduct FFT on angle-domain determined function? Which modifications should I apply to my data?
Thank you!
EDIT sample FFT magnitudes are added
