Question

If the two atoms are pulled apart, show that they will separate most easily when r = (28b/a)^1/6.

Answer 1

Force, F = −dV/dr = a/r² − 7b/r⁸ 

The particles will separate most easily when the force between them is a minimum, that is when dF/dr = 0. 

This gives: dF/dr = −2a/r³ + 56b/r⁹ = 0 

r = (28b/a)^1/6