WELCOME TO THE HYDROGEN ATOM DEMO

This program generates volume data that represents
the probability density of the electron of a
hydrogen atom. The volume data is a 3 dimensional
array, with each cell in the array representing a
small volume of space located at that cell's x, y,
z location.  The value in each cell represents the
likelyhood of finding the electron in that cell's
space at a given instant in time.  Zero represents
no probability, and one represents complete
probability.

The probability of finding the electron is governed
by three quantum numbers, n, l, and m.  Although a
full discussion of the meaning of these quantum
numbers is beyond the scope of this message, some
brief notes may give a little insight into their
function:

     The energy is proportional to n^2

     The square of the angular momentum is
     proportional to l(l+1)

     The z component of the angular momentum is
     proportional to m

QUANTUM NUMBER CONTROLS
-----------------------

Move the n, l, and m sliders to change the quantum
numbers used to generate the volume data.

DISPLAY CONTROLS
----------------

<<Depth Cueing>> checkbox
Check this box to make axes and isosurfaces fade
toward the background color with distance.

<<Color Smoothing>> checkbox
Check this box to enable color interpolation.
Trilinear interpolation is used for voxel
projections.   Gouraud shading is used for
surfaces.

<<Data Resolution>> slider
Move this slider to set the number of voxels to
calculate.  For example, 35 yields a 35x35x35 voxel
volume. 100 yields a 100x100x100 voxel volume.
Each voxel value represents the probability of
finding the electron in an infinitesimal volume at
that voxel's x, y, z location, at a given instant
in time.

<<Color Table>> list
Select color tables to be used in graphic.

<<Show Voxel Projection>> checkbox
A voxel projection is a volume display that
typically looks like a translucent cloud.  Each
voxel in this program's volume has color and
opacity per its probability value.  Voxels occlude
those that are behind them to the extent that they
are opaque.

<<Approximate Overall Opacity>> slider
Move this slider to scale the opacities in the
volume.  Overall opacity is an estimate of how much
the the entire volume blots out that which is
behind it (i.e the background).

<<Show Isosurfaces>> checkbox
Isosurfaces are sets of contiguous polygons
enclosing voxels that exceed a given threshold.
Check this box to show isosurfaces.  Click in the
outlined region to the right of the colorbar to
create new isosurface thresholds.  Drag the
resulting wedge-shaped indicators to move
isosurface thresholds.  Right click a wedge-shaped
indicator to remove that isosurface threshold.

<<Isosurface Style>> droplist
Select from this list to specify how isosurface
polygons should be drawn.  The "Perforated Surface"
style is created using texture maps.

<<Auto Refresh>> checkbox
Check this box to have the program automatically
update its calculations (when needed) and redraw
the volume after each change you make with the
mouse.

<<Refresh>> button
Click this button to update the volume and display.

COLORBAR WITH MULTISLIDER 
-------------------------

When the Show Isosurfaces checkbox is checked, an
outlined region appears to the right of the
colorbar in the graphic.  Click in the outlined
region to create new isosurface thresholds.  Drag
the resulting wedge-shaped indicators to move
isosurface thresholds.  Right click a wedge-shaped
indicator to remove it.


References:

Quantum Theory
David Bohm
ISBN: 0-486-65969-0

Modern Physics
Kenneth Krane
2nd ed. pp. 208-219
ISBN: 0-471-82872-6