What is the change of variables for Lennard-Jones potential?

[Lavace]

Homework Statement

[PLAIN]http://img94.imageshack.us/img94/4287/len2.jpg

Homework Equations

[PLAIN]http://img710.imageshack.us/img710/2428/len1y.jpg

The Attempt at a Solution

I know my way around the Lennard-Jones potential formula, but this question stumps me.

Any clues on how to proceed are greatly thanked!

 

[nickjer]

Just define a new unitless variable as $X=r/\sigma$.

 

[Lavace]

Just define a new unitless variable as $X=r/\sigma$.

I used your defined variable and plugged it in, but still cannot arrive at the proof given in the question, could you possibly expand further?

Thank you!

 

[nickjer]

I wouldn't call that a proof. You are just doing a change of variables. You can replace $r/\sigma$ with $X$ in the above equation. Unless 'X' has a meaning that I am unaware of.