Re: [Phys-L] Energy & Bonds

[Bruce Sherwood <Bruce_Sherwood@ncsu.edu>]

Lest there be any misunderstanding, note that JD is plotting potential
energy for (charged) ions bound to each other, not neutral atoms bound to
each other. For the latter case, a well-known approximation is the Morse
potential energy (http://en.wikipedia.org/wiki/Morse_potential) for which a
harmonic oscillator well fits over a much wider range of distances than it
does for the two-ion situation.

Bruce

On Fri, Nov 15, 2013 at 4:27 PM, John Denker <jsd@av8n.com> wrote:

> Yesterday on 11/14/2013 01:59 PM, I wrote:
>
> > Note the contrast:
> >  -- The amount of /energy/ we have to put in to move
> >   two previously-bound ions apart approaches a maximum
> >   at large R.  Draw the graph of a -1/R potential.
> >        http://www.av8n.com/physics/img48/ion-energy.png
> >   Don't forget the minus sign, and don't forget
> >   that -1/R is not the right answer at small R.
> >  ++ Contrast this with the  ½ k R^2  potential for a
> >   Hookean spring.