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Running the surface diffusion/desorption code with the -help option yields the following output describing the command-line options:
mccode <seed> <coverage> <grid x> <grid y> <print freq> <refinement>
<temperature> <timesteps> <geometry>
seed - random seed for the RNG
coverage - in percentage
grid_x,grid_y - dimensions of the grid space
print freq - frequency with which to print out data ( <=0 implies no prints)
refinement - refinement level for spatial binning
temperature - in degrees Kelvin
timesteps - number of steps of MC time
geometry - --no-step or --two-step
The seed parameter is the number used to seed the random number generator.
The coverage parameter represents the percent of grid sites containing hydrogen atoms at the start of the simulation.
The grid x and grid y parameters define
the number of grid sites in the 
and 
directions. Note that
grid y must be divisible by eight, and that both must be
divisible by the refinement parameter.
The print freq parameter defines the frequency (in terms of number of MC steps) with which to print out position data for the particles. A negative or zero value of this parameter indicates that this information will never be printed out.
The refinement parameter sets the refinement level for the spatial binning, i.e. the number of grid sites in each dimension included in each spatial bin. This must divide both grid x and grid y evenly.
The temperature parameter represents the system temperature in degrees Kelvin.
The timesteps parameter sets the number of MC timesteps for which the simulation will be run.
The geometry parameter sets the type of geometry to use. The
first type of geometry is the ``no-step'' geometry, which runs the
simulation on a single, flat terrace with horizontally aligned dimer
rows. The second type of geometry is the ``two-step'' geometry which
has an A-step a quarter of the way across the domain in the
-direction and a B-step three quarters of the way across the domain
in the -direction.