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Van der Waals Potential

  • Thread starter Fr3shFr0st
  • Start date
  • #1

Homework Statement


The van der Waals potential between two inert atoms is often characterized by the expression:

http://bama.ua.edu/~stjones/253hw_files/image025.gif [Broken]

Sketch the function. Expand the potential around the minimum in the form U = U(ro) + ½ k(r-ro)2. Evaluate k in terms of s and e.



Homework Equations


Above


The Attempt at a Solution


I got the sketch down fine. I am just unclear about the second part. Nothing in my physics textbook helps. What i have done so far is take the original equation and substitute it in
U = U(ro) + ½ k(r-ro)2. Doing that i got:

U = 4e[(σ/ro)^12-(σ/ro)^6] + ½ k(r-ro)2

From there i solved for k and got:

k={U-[4e[(σ/ro)^12-(σ/ro)^6]]/(r-ro)^2}*2

Im not sure if im the right path but from here i dont know how to get k in terms of s and e. Any help is greatly appreciated!
 
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Answers and Replies

  • #2
Redbelly98
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Are you familiar with Taylor Series expansions (from when you took calculus)? That's the key to solving this one.
 

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