1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

L-J Potential-Distance of equilibrium

  1. May 31, 2013 #1
    LJ-Potential

    1. The problem statement, all variables and given/known data
    Find distance of equilibrium for:
    1.
    Uvdw(r)=-A/r6+B/r12
    A=10-77 Jm6
    B=10-134 Jm12



    2. Relevant equations

    Uvdw(r)=-A/r6+B/r12

    3. The attempt at a solution
    It is suppose that r is the distance, but I have not any idea how to calculate this.

    appreciate your help
     
  2. jcsd
  3. May 31, 2013 #2

    berkeman

    User Avatar

    Staff: Mentor

    This article may help: http://en.wikipedia.org/wiki/Lennard-Jones_potential

    This isn't really an engineering question, though. Would you like me to move this to the HH/Advanced Physics forum?
     
  4. May 31, 2013 #3
    1. The problem statement, all variables and given/known data
    Find distance of equilibrium for:
    1.
    Uvdw(r)=-A/r6+B/r12
    A=10-77 Jm6
    B=10-134 Jm12



    2. Relevant equations

    Uvdw(r)=-A/r6+B/r12

    3. The attempt at a solution
    It is suppose that r is the distance, I suppose that r=(2A/B)(1/6)
    and 0=2A-Br6.
    However I`m totally lost

    appreciate your help
     
    Last edited: May 31, 2013
  5. May 31, 2013 #4
    Thanks
     
  6. May 31, 2013 #5

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    The equilibrium distance is the minimum of the potential. How do you find a minimum?
     
  7. Jun 3, 2013 #6
    ok, finally I figure out how to calculate the minimun which is r = (2^(1/6) B^(1/6))/A^(1/6). Am I right?
     
  8. Jun 3, 2013 #7

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Looks good. I would express it as ##\displaystyle \left(\frac{2B}{A}\right)^{\frac{1}{6}}##
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: L-J Potential-Distance of equilibrium
  1. Calculating J,L,S (Replies: 7)

Loading...