The electron distribution in silicon. A comparison between experiment and theory

Abstract

T. JANSSEN 271 would give the 12 vertices of an icosahedron and locally icosahedral symmetry, which is, of course, in conflict with periodicity, but as we have seen not with quasi-periodicity. I thank J. C. Toledano, R. Struikmans and the referee for pointing out relevant references. AbstractDeformation and valence-electron densities in silicon are derived via Fourier summation and multipole refinement of highly accurate measurements of X-ray structure factors. These results provide a new perspective for the comparison between theory and experiment. The model electron density derived from experiment is in quantitative agreement with recent solid-state calculations, but not with earlier experimental results reported by Yang & Coppens [Solid State Commun. (1974), 15, 1555-1559.

X-Ray diffraction studies on electron density in organic crystals

“…110 The causes of the systematic absence of peaks on bonds of the C -F and Ο -Ο types as well as certain others 7 were indicated above in Section III. The splitting of the peak on bonds formed by a silicon atom (Si-Si, 26 Si-Cl, 102 and Si-C 108 ) is sometimes also observed.…”

“…26 The experimental determination of the initial phases on the basis of three-wave diffraction apparently represents the most promising aspect of studies of this kind. However, despite the clear advantages of the direct experimental methods for the determination of the initial phases listed above, they still remain too complex to hope for their rapid and extensive application on a large scale.…”

Calculation of the electron density distribution in silicon by the density-functional method. Comparison with X-ray results

“…Nevertheless the values are close to the measured values in crystalline silicon: Spackman (1986) reported a value of 0.206 e A -3 and Scheringer (1980) of 0.20 e A -3. The measured value of Price, Maslen & Mair (1978), corrected by Spackman (1986), for the maximum in zip is 0.20 e A -3. Saka & Kato (1986) reported a slightly larger value of 0.221 e A -3 which is a direct consequence of their use of the 222 reflection from Fehlmann & Fujimoto (1975).…”

“…This is all the more interesting because the calculations can be compared with the very accurate structure factors of silicon, obtained by Aldred & Hart (1973) and by Saka & Kato (1986) with the Pendel16sung method. Spackman (1986) has analyzed various sets of measured structure factors and compared them 0108-7681/89/040359-06503.00 with different theories, while Cummings & Hart (1988) have recently reanalyzed the experiments of Aldred & Hart (1973)making some additional corrections.…”

“…To verify the assumption and to judge the resulting crystalline electron density ffistdbution, structure factors were calculated and compared with the results of Pendell6sung measurements by Aldred & Hart (1973) and Saka & Kato (1986), with values recommended by Spackman (1986) on the basis of careful analysis of existing data, and with the outcome of Yin & Cohen's (1982) band-structure calculations.…”