XRAYDIF1 by Todd Warren Snyder 14727 Polk Street Omaha, NE 68137 email: mermtws@engvms.unl.edu What is XRAYDIF1? XRAYDIF1 is a shareware version of my theoretical, x-ray powder diffraction, profile simulator. It is intended as an inexpensive substitute for data-based, powder diffraction profile generators, and as a teaching tool. Benefits XRAYDIF1 has the capability to simulate a diffraction profile for any crystalline element or compound. The output is available as an interactive graphics display as well as an extensive peak summary data file (trace.dat). It has been tested on hundreds of elements and compounds with superb agreement of peak locations. Limitations This shareware version of XRAYDIF1 has only one limitation with respect to the registered version. It can simulate only pure elements or two-element compounds. i.e, NaCl, FeO3, Cu... but not MnSO4 or BaTiO3 The registered version is capable of any element or compound! XRAYDIF1 also neglects temperature effects. Use XRAYDIF1.exe is a DOS program and runs in VGA mode. The graphic output may be printed by using graphscr or hpgraph or any other TSR graphics print program from dos. The graphic output may also be captured to the clipboard during a windows DOS session by hitting print-screen. The only output file is a text file called "trace.dat" which summarizes the results of the current simulation. The on-screen instructions are self explanatory, but here are two examples: Simulation of iron pattern and simulation of rutile pattern. 1) Simulation of alpha iron pattern. STEP A - start program by typing "XRAYDIF1" from the directory where it resides. Hit Enter, then WAIT about 5 seconds. STEP B - Enter the x-ray tube target material used for the generation x-rays. The default, and most common is Cu. Hit enter. STEP C - Enter the necessary lattice angles. Since alpha iron is cubic all angles are 90 degrees, the default. Hit enter three times. STEP D - Enter the necessary unit cell edge lengths.(lattice parameters) Since all lengths are equal just enter the first one, a. Type "2.8665" and hit enter. Hit enter twice more, the b and c lengths will default to 2.8865 angstroms. STEP E - Enter the number of elements. Type "1" and hit enter. STEP F - Enter the number of atoms per unit cell. Since alpha Fe is body-centered cubic, there are two atoms per unit cell. 8*(1/8)+1=2. Type "2" and hit enter. STEP G - Enter the atomic number(s). Type "26" and hit enter. STEP H - Enter the positions of the atoms. The body-centereed cubic structure has atoms at positions (0,0,0) and (.5,.5,.5). Type "0,0,0" and hit enter. Type ".5,.5,.5" and hit enter. STEP I - The graphical output is now on the screen. Use the greater-than and less-than keys to scroll through the peaks. A "." will appear above each peak in turn and the position/intensity/hkl values will also change accordingly at the top of the screen. 2) Simulation of rutile (TiO2) pattern. STEP A - start program by typing "XRAYDIF1" from the directory where it resides. Hit Enter. WAIT STEP B - Enter the x-ray tube target material used for the generation x-rays. Lets use a Cr tube. Type "2" and hit enter. STEP C - Enter the necessary lattice angles. Since rutile is tetragonal, all angles are 90 degrees, the default. Hit enter three times. STEP D - Enter the necessary unit cell edge lengths.(lattice parameters) Enter the first one, a. Type "4.59" and hit enter. Hit enter once since b=a or type "4.59" and hit enter. Enter c. Type "2.96"and hit enter. STEP E - Enter the number of elements. Type "2" and hit enter. STEP F - Enter the number of atoms per unit cell. There are six atoms per unit cell, 2 Ti and 4 O. Type "6" and hit enter. *NOTE THE FLASHING INSTRUCTIONS* STEP G - Enter the atomic number for element 1. The Ti is at a 4+ valence. For the 1st element (Ti), type "18" and hit enter (22-(+4))=18. STEP H - Enter the number of atoms of element 1. Type "2" and hit enter. STEP I - Enter the positions of the element 1 atoms. The Ti atoms are at (0,0,0) and (.5,.5,.5). Type "0,0,0" and hit enter. Type ".5,.5,.5" and hit enter. STEP J - Enter the atomic number for element #2. The O is at a 2- valence. For the 2nd element (O), type "10" and hit enter (8-(-2))=10. STEP K - Enter the number of atoms of element #2. Type "4" and hit enter. STEP L - Enter the positions of element #2 atoms. The O atoms are at (-.3056,-.3056,0),(.8056,.1944,.5), (.3056,.3056,0), and (.1944,.8056,.5). Enter these values. STEP M - The graphical output is now on the screen. etc REGISTERING - PLEASE DO. I think $20 is a reasonable amount for a single user. I would expect that if XRAYDIF1 was used for teaching or in an industrial setting, the institution could benefit $50 worth. I would also negotiate the source code. Te register send your return address, ph# ... along with payment to: Todd Warren Snyder 14727 Polk Street Omaha, NE 68137 I will send you a 3 1/2 disk without the '2-elements' limitation.