## PHY 346 -- Computational Physics Lab

 Instructor: Natalie Holzwarth Phone:758-5510 Office:300 OPL e-mail:natalie@wfu.edu

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 use ssh or putty to log into deach01.deac.wfu.edu and it will be extremely helpful to load the following old version of win32 in order to access graphics interfaces within the windows environment. (If your machine can boot to linux, the graphics capabilities should be automatic.) In addition, you may find the following files helpful.

Here are some notes and some more notes on some basics of numerical analysis.

Lab assignment for first session (4/6/06)

Pick at least one of your favorite atoms from the periodic table and run the computer program graphatom ( available on deach01.deac.wfu.edu on /home/natalie/Coursework/atomic/code/graphatom ) to determine:

1. A plot of the electron density for that atom.
2. A plot of the one-electron wavefunctions (labeling the curves -- 1s, 2s,... 2p, 3p... etc.)
3. 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. You should compare your results with experimental values, such as listed at NIST.

(Please send email to natalie@wfu.edu if you have any questions.)

Lab assignment for second session (4/13/06)

This assignment involves running a molecular dynamics simulation found on deach01.deac.wfu.edu on /home/natalie/Coursework/md/code/md.exe. This program assumes allows you to construct a random arrangement of atoms in a volume. The atoms are assumed to interact with eachother via a simple pairwise force. From the initial atomic arrangement and initial velocities, the program "evolves" the particles according to Newton's laws. At each time step, the coordinates are printed to file which can later be visualized using the program xcrysden. The brief notes may be useful.

#### 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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