PHY 346 -- Computational Physics Lab
General Information:
These lectures and labs present a brief introduction to computational physics
using examples from self-consistent field calculations of the electronic
energy and density of various atoms throughout the
periodic table. In order to prepare for the assignment, you will
need to load some software on your computers as explained in the
instructions.
Here are some notes and some
more notes on some
basics of numerical analysis.
Lab assignment for first session (3/1/05)
Pick at least one of your favorite atoms from the
periodic table and run the computer program
graphatom
( ~natalie/www-home/s05phy346/program/graphatom )
to determine:
- A plot of the electron density for that atom.
- A plot of the one-electron wavefunctions (labeling the curves -- 1s, 2s,...
2p, 3p... etc.)
- A list of the total energy and the one-electron eigenvalues for the ground
state and at least one excited or ionic state. Note
-- the energy units are Rydberg == 13.60569172 eV. In the next meeting, we
will compare your results with experimental values.
(Please send email to natalie@wfu.edu
if you have any questions.)
Lab assignment for second session (3/17/05)
In this session, we will focus on running the program graphatom for a
few materials and comparing the results with experimental ionization energies
or excitation energies.
- Run graphatom for your favorite atom in its ground state and at
least one excited or ionized state, comparing the energy differences between
the frozen core, relaxed core, and experimental result.
One source of experimental data is
available from NIST.
- Compare the shapes of at least two
of the wave functions in the ground and excited or ionized state. For this
purpose, it will be helpful to make two subdirectories. For example, you
can issue the commands:
mkdir groundstate
cd groundstate
graphatom
(input appropriate data)
cd ..
mkdir ionizedstate
cd ionizedstate
graphatom
(input appropriate data)
cd ..
gplot -f ./groundstate/wfn0 1 4 lines -f ./ionizedstate/wfn0 1 4 lines
In this example, the gplot command allows you to plot the s-like wave
functions (stored in the files named wfn0). The numbers "1 4"
mean that you are plotting the results in column 1 (r-values) versus the
results in column 4 (in this case, the 3s radial wave functions).
- Extra credit
Using the density results for an atom of your choice, calculate the
X-ray form factor as a function of scattering wavevector q.
Computer Programs
graphatom
Note: In order to run these programs, you will need to run X-Win32
and SSH as described above. Within the SSH windown, login to the wfu.edu computer
using your login ID and password.
List of some useful commands
- man (command name) -- on line help information. If you don't
know the command name, you can type "man -k (topic name)"
- ls -l -- lists the file names in your directory
- cat (file name) -- lists file contents
- more ( file name) -- same as "cat", but pauses at the end of each
screen full of data.
- lpr -Polin305 file name -- sends file to printer
- chmod 755 plot* -- this makes all files beginning with the
filename "plot" into executable files
- which program name -- the result of this command will tell you
whether you can "find" the program you wish to execute.
- echo $PATH -- this will display which directories are accessed when you
type commands.
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