Once a finite difference algorithm is chosen and implemented, one must
determine a suitable time step, **dt**, for the simulation. A ``good''
time step is large enough that the system evolves rapidly, yet small
enough that the finite difference algorithm is accurate. There is no
inherently ``good'' time step--- rather, the size of an appropriate
time step depends on the system being simulated. In this simulation,
the user has three options for selecting a time step. These options, accessed
by the mouse sequence ` Parameters Numerical` are:

- Scale the time step by the period of the micromotion.
- Scale the time step by the Einstein period.
- Implement a user-specified time step.

Fri May 12 10:36:01 EDT 1995