           EXAMPLE SIMULATION PROJECT: 600 eV Xe -> Mo(100)
            ================================================

This directory contains SNOOK project files for a simulation
of 600 eV Xe bombardment of a Mo(100) surface at normal incidence.
You can load the files into SNOOK and run immediately, or you
can tailor them to your own purposes using SPIDER.

The Mo target consists of an 11x11 atom surface which is 8 layers
deep (968 atoms).

The simulation involves 625 trajectories directed into a region
of area 1.573 x 1.573 A (1/4 of the bulk unit cell), and takes about
5 hours to run on a 120 MHz Pentium with 16 MB of RAM. The output
file (DYNVARS.SNK) will be 22 MB in size, and will contain the
trajectories of all particles at termination of every one of the
trajectories.

This is a big project that will take many hours to run.

You can modify the output behaviour by editing MO100.RUN with
SPIDER.EXE (RUN option on menu). For example, you could choose
to output coordinates for ejected particles only, i.e. the 'All
emission' option in SPIDER's RUN menu. This would reduce the output
ile size to under 3 MB (estimated). MO100X.RUN implements
this option, if you prefer this (use it in place of MO100.RUN).

If you want to do a short test run, use the file MO100X.IMP in
place of MO100.IMP: this will generate 16 trajectories into the
same surface zone (1/4 bulk unit cell).

Strictly speaking, for normal incidence there is no need to sample
1/4 of the unit cell: symmetry reduces the unique trajectories to
a zone of 1/8 the unit cell. However, if you use a projectile off
normal incidence but parallel to [001], then you must use 1/4 of the
cell.

The file MO100.DOC shows the atomic positions at the end of one
simulation run for this system.

Annexe: Simulation conditions used for MO100 project
====================================================

[ You can also read this information from the project files if
 you load them into SPIDER.EXE ]

600 eV Xe -> Mo(100) at normal incidence
Initial timestep = 0.6 fs
Interaction potentials:
Xe-Mo: ZBL potential (all R)
Mo-Mo: ZBL potential for R < 1.8 A
       Morse potential for R > 2.7 A
       Spline function for 1.8 A < R < 2.7 A.
       Note: the spline limits were determined by trial and error.
       This involves 'guessing' the limits, then examining the
       smoothness of the resulting potential and force curves
       (data is output by SPIDER to the files FORCE.SPL and
       POTENTL.SPL respectively when you create a MDL file).
Potential/Force cut-off: 4 A.
Termination conditions: KE < 1.5 eV or elapsed time > 500 fs.
Thermal vibrations included: Yes.

The Morse potential parameters and other atomic data were read from
SPIDER's online Help.


