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Postings for `debye': x-ray scattering in one dimension in perfect and imperfect crystals

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  • 5.2 -- 3/19/99 -- Bug in NEW version --but see update 1.11
    With the revision of the software which allows use with lower resolution screens we have also managed to add a few bugs into the programs. You may receive an error message when you try to open the "configuration" window. To fix this problem download: and replace the debye.tcl file in your sss/lib/debye folder with this corrected file. (This bug is on the CD with the revised program and on earlier versions of our updaters which replace the original (high resolution only) version of the software with the newer version. It is NOT on the original SSS CD.)


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  • 5.1 -- 10/29/98 -- Problem 5.8
    We would like to know the answer to exercise 5.8 in "debye", which asks for an explanation for why the two transverse modes propagating in the (111) direction of an fcc crystal are degenerate.
    -----RDD

    Professors always prefer to answer questions with a second question. In this case I would ask a student to find the three normal modes of vibration of an equilateral triangle of three equal masses connected by three springs all of the same strength, and ponder over why two of the modes, for which the displacement patterns look quite different, should have the same frequency.
    -----RHS


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