Using the Kellermann model of the NaCl crystal, the eigenfrequencies of NaCl have been found for a sub‐division of 12, 16, 18, 24, 36, and 48 of the wave vector along each axis of the reciprocal cell. From these frequencies the frequency distribution has been found, using the usual sampling technique. A comparison of these distribution functions is given. Assuming the results of the 48 division to be correct, the percentage errors of the other distribution functions based on fewer frequencies have been found as a function of the number of frequencies per frequency interval. From these results, the accuracy of the 48‐division calculation has been estimated. The calculated heat capacity at constant volume changes by about 3% at 10°K due to the various frequency distributions, but above 20°K the values agree within four significant figures.

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© 1963 American Institute of Physics.
1963
American Institute of Physics
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