In solid state physics, a popular example of the interaction between noble
gas atoms is the The Lennard Jones Potential . This interaction is clearly
presented in "Introduction to Computer Simulation Methods: Applications to
Physical Systems" by H. Gould and Jan Tobochnick 2nd edition as:
V(r)=4*E*[(s/r)^{12} - (s/r)^{6} ], with the force
associated with this potential written as F(r)=24*E*[2*(s/r)^{12}
-(s/r)^{6}] __r__, where E and s are the energy and distance
parameter associated with this model.In the case of Argon, s=3.4x10^{-10}
meters, E=1.65x10^{-12} Joules, m=6.69x10^{-26} kg. However,
in this calculation, we use units of e_b=1x10^{-19} Joules,
distance units of a_b=1x10^{-10} meters, mass units of m_b=1e-26
kg; so that, the time units are a_b*(m_b/e_b)^{1/2} . The
simulation is done in one dimension. Finally, the simulation shows one
atom fixed at the origin, another atoms sitting at an initial position. As
the simulations is started, the molecules begin to interact as indecated
by the motion of the right particle. The graph shown indicates the
position of the moving particle as a function of time. Notice that the
particle oscillates about an equilibrium point. This equilibrium point is
actually the average distance between the particles known as the bond
length. The simulation is capable of displaying the value of the
particle's velocity as a function of time and the particle motion can be
traced as well, all by checking the appropriate interactive bottons.