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CAF123
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Homework Statement
Consider the interatomic potential between 2 atoms: $$U(r) = U_o \left[exp\left(\frac{-2(r-a)}{a}\right) - 2exp \left(\frac{-(r-a)}{a} \right) \right],$$ where r is the separation between the two atoms and ##U_o## and a are constants.
1)Evaluate the expressions in the square brackets for a number of values of r/a and thereby make a plot of U(r)/Uo versus r/a, plotting the two exp terms separately.
2)Sketch the total result on the same diagram.
The Attempt at a Solution
I have attached two graphs of the attractive and repulsive component of this potential. Conveniently, the potential can be expressed in the form y =y(x), with y = U/Uo and x =r/a. I don't know what a is so I am struggling to see if my graphs make any physical sense. As r/a decreases, however, I note that the repulsive term increases with limit of e2 in the repulsive case and -2e in the attractive case. To obtain these graphs, I simply plotted the two exp terms against r/a separetely, for random values of r/a. Can someone check these graphs?
Also, I am a bit unsure of how to combine them into one graph.
Many thanks.