High-momentum components and temperature dependence of the Compton profile of beryllium -: art. no. 085104

We present Compton-scattering studies on the high-momentum components of the valence electron momentum density in beryllium. The experiments were performed with incident photon energies of 29 and 56 keV with a momentum space resolution of 0.10 and 0.16 a.u. units of momentum, respectively. The temperature dependence of the Compton profile and the high-momentum components were studied within the temperature range of 40-850 K. The incident photon energy was 56 keV and the photon scattering vector was along the [110] reciprocal lattice vector. We compare the temperature dependence of the experimental Compton profiles to empirical local pseudopotential computations that take into account both thermal expansion and disorder. The position and intensity dependence of the high-momentum components as a function of temperature in solid beryllium were found to be quite small, which suggests that the valence electron wave functions in beryllium are not significantly affected by thermal disorder. This proves that the previously observed broadening of experimental Compton profiles in comparison to highly accurate theoretical profiles is not due to thermal disorder, and other reasons, e.g., correlation, need to be sought as the source of the broadening.