The potential energy of two atoms in a diatomic molecule is approximated by
U(r)=a/r^12 - b/r^6,
where r is the spacing between the atoms and a and b are positive constants.
Find the force F(r) on one atom as a function of r.
Make two graphs one of U(r) versus r and one of F(r) versus r.
F(r) = -(dU/dr)
The Attempt at a Solution
I know F(r) = -(dU/dr).
So, F(r) = (12a/r^13) - (6b/r^7)
And then I get stuck. I don't know how to make a plot of U(r) vs r and F(r) vs r when I don't know a and b.
I want to plug values of r=[0.1, 0.2, 0.3, ...] into the F(r) equation, but I have no idea what to do about a and b.
This question has been asked before on this forum and I have looked at the hints, but I am still completely lost.
Could someone please get me pointed in the right direction.