# Lennard Jones Potential Equation: Repulsive and Attractive terms?

1. Aug 9, 2009

### Lavace

http://www.ph.qmul.ac.uk/phy108/CM2008_week2_exercise1_solution.pdf [Broken]

The L-J Potential Curve in question 2),

V(r) = V(r) repulsive + V(r) attractive

Is the ^12 term the repulsive term and ^6 is the attractive term?

Last edited by a moderator: May 4, 2017
2. Aug 9, 2009

### gabbagabbahey

Well, $\textbf F=-\nabla V$....what sign does an attractive force have? Which term in the potential produces a force with that sign?

3. Aug 9, 2009

### Redbelly98

Staff Emeritus
Alternatively, keeping in mind that the force acts in the direction of lower potential:

Image a graph of 1/r12. Is that an attractive or repulsive potential?

Do the same for a graph of -1/r6