This is an introduction to the part on Visualization of Atomic Collisions Calculations.
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We have chosen this quatation as a motto for this work
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persp.gif
This is a picture describing the basis of the (semi) classical
collision theory. On the next picture, the plane is
rotated into the screen plane.
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plane.gif
The collision plane, seen on the previous perspective drawing,
rotated into the screen plane .. .. .. .. ..
tdsep1.gif
The theory: Time dependent Schroedinger equation relevant for the
collision process. The expansion in a basis set is shown.
Also shown are the kinetic energy of the electron and the two
potentials, describing the interaction with the target and the
projectile. .. .. .. .. ..
expand.gif
Using the expansion and evaluating projections on the basis states,
one obtains a set of coupled equations
for the coefficients as functions of time. .. .. .. .. ..
eq1.gif
In most cases, one is satisfied by obtaining the expansion
coefficients, since the occupation probabilities (and the experimentally relevant quantities)
can be obtained from them. However, there is also the
concept of probability density and probability density current.
These two quantities are defined above.
To obtain them, we must use the basis states
in "all points", i.e. on a certain mesh. This is an
additional computational effort, which cannot lead
to any comparison with experiment.
It can, however, provide cllues for understanding of the mechanisms.
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plane.gif
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dens.gif
This is a plot of probability density. Each new pattern is factor 2 down, i.e.
exponential scale with steps of log 2.
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curr.gif
This is the corresponding probability density current. .. .. .. .. ..
denscur.gif
Here the two previous are compared. .. .. .. .. ..
eq1.gif
Once more the definitions...... .. .. .. .. ..
3pp3pm.gif
This is a cut from a movie, which one can run in task 5. This particular
picture compares two densities toowards the "end" of the collision.
The difference is in the starting condition:
The upper starts in "3p-" state, the lower in "3p+ state.
See on the next picture what does it mean in terms of currents.
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strom1.gif
These are the coresponding currents "before" the collision. The picture
tells more than words and formulae.
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3pp3pm2.gif
Now that collision is "finished".
Can you describe the difference? Can it be understood (or
made probable) using classical arguments?
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alig.gif
Another starting point: the states are prepared in alligned states.
What will be the difference now?
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1s2s.gif
Here and in the following are pictures
of densities (and at the end 1 current),
constructed from simple amplitudes, equal to 1.
These plots show the hydrogenic
state densities. .. .. .. .. ..
2pand2p.gif
Here and in the following are pictures
of densities (and at the end 1 current),
constructed from simple amplitudes, equal to 1.
These plots show the hydrogenic
state densities. .. .. .. .. ..
1dens.gif
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1curr.gif
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