To have an understanding of many imaging and diffraction effects relating to high-energy electrons it is essential to take into account the vibrations of the atoms of the solid being examined. Einstein's model of the vibrations takes the atoms to be independent oscillators. Debye's model includes the effects of correlated atomic motion and is more accurate in describing simple solids. Electrons which exchange energy with the solid through a change in the vibrational state of the solid are incoherent with respect to the incident electron wave and may be considered as being absorbed out of the incident wave field. Yoshioka and Kainuma showed how to calculate the components of the absorptive potential, which is imaginary rather than real, and pointed out that they depend on the direction of the incident wave. The components of the imaginary potential vgh(im) are not simply a function of g-h, unlike those of the real potential describing elastic scattering. Here g and h represent vectors in reciprocal space. Using Debye's model and assuming that the speeds of the three components of acoustic waves in the solid are equal we find