Comparison of Theoretical and Experimental Charge Densities for C, Si, Ge, and ZnSe

The electron distribution in diamond: a comparison between experiment and theory

“…Larger basis sets with polarization functions included would be likely to yield better agreement with experiment, but we note that the 6-21G* basis set used by Orlando et al (1990) overestimates the bond peak in the deformation density, and hence is likely to do the same for F222. The self-consistent orthogonalized plane wave (SCOPW) calculations of Raccah et al (1970) are clearly somewhat inferior to the other methods, as in all four cases presented in Table 4 F222 is well described (values between 0.12 and 0.14e) yet R factors are higher than for the other methods. Ivey (1974) has commented that the SCOPW calculations cannot adequately handle systems without core p (1980) 1"62 9 Heaton & Lafon (1978) 2.15 9 Zunger & Freeman (1977) states (e.g.…”

“…We compare twelve calculations of structure factors taken from vonder Linden, Fulde & Bohnen (1986), Dovesi, Pisani, Ricca & Roetti (1980), Heaton & Lafon (1978), Zunger & Freeman (1977), Ivey (1974), Euwema, Wilhite & Surratt (1973) [actually the 'refined' results reported by Ivey (1974)] and Raccah, Euwema, Stukel & Collins (1970). In Table 4 we give unweighted R factors (R=YllFexpl-IF,.oorll/Y~lf~xpl) for these theoretical calculations.…”

The electronic charge densities in semiconducting layer and chain structures

“…They have shown that in spite of the deviations of pseudowavefunctions from the exact one-electron wavefunctions such as are e.g. derived from the selfconsistent orthogonal plane-wave model [4) a very satisfactory description of the distribution of the valence electrons in the lattice can be obtained: In regions outside the atomic cores the pseudo charge densities are qualitatively correct. Their pictorial representations therefore afford a confirmation or infirmation of the chemist's image of the bonding in solids.…”

The electronic charge distribution in crystalline silicon: comparison of ab initio theory and experiment

“…While the second approximation could be partially circumvented by adding the core structure factors to the pseudo-valence structure factors, this procedure ignores core-valence orthogonality and leads to systematic errors noted by Spackman (1986). All-electron calculations, which treat core and valence wavefunctions on equal footing (Raccah, Euwema, Stukel & Collins, 1970;Wang & Klein, 1981;Dovesi, Causa & Angonoa, 1981;Heaton & Lafon, 1981;Weyrich, 1988;Methfessel, Rodriguez & Andersen, 1989;Polatoglou & Methfessel, 1990), are free from such complications. However, some of them involve independent approximations such as perturbation theory (Bertoni et al, 1973) or the use of small basis sets (Dovesi et al, 1981;Heaton & Lafon, 1981).…”