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Two programs have been developed to calculate the one-phonon thermal diffuse scattering included in measured integrated intensities of Bragg reflections for cubic crystals. Both include the anisotropy of the diffuse scattering correctly within the continuum elasticity approximation, and both allow an approximate inclusion of the effects of the wavelength distribution of the primary beam. One program, restricted to co-scans, includes primary beam divergences approximately using three experimental reflection profiles to describe the weighting function in reciprocal space. The second program, applicable to both co-scans and 0: 20-scans, neglects the primary beam divergences but has the advantage of being approximately two orders of magnitude faster than the first. Calculations have been made with these programs for several cases to illustrate the dependence of the included thermal diffuse scattering correction on various factors and to compare with the values obtained from previous approaches.

Temperature diffuse scattering of x-rays (TDS) has been examined in cubic powders to test the reliability of current TDS theory. Measurements are reported of the diffuse scattering of copper and lead along with the Bragg reflections of these metals at room and liquid nitrogen temperatures. These measurements were made using a scintillation counter diffractometer and crystal monochromated CuKe< radiation. The TDS so otained is compared with TDS calculations based on the one-and two-phonon calculation as well as on the Warren (modified one-phonon) calculation. Both formulas are found to fit the magnitude of TDS by choosing appropriate Debye characteristic temperatures. The Debye 8's which fit the copper and lead TDS data at room temperature are: 324 0 and 96 0 (one-and two-phonon) and 269 0 and 64° (Warren formula) as compared to values of 307 0 and 79 0 taken from the temperature dependence of the Bragg reflections and 315 0 and 88 0 from specific heat values for copper and lead, respectively. Evidence is also found for extra diffuse scattering in the low-angle region. This extra scattering is tentatively ascribed to a multiple scattering process.