Compton profiles of Si: Pseudopotential calculation and reconstruction effects

Abstract

Using an ab initio pseudopotential calculation, we compute Compton profiles of silicon along the ͑100͒, ͑110͒, and ͑111͒ directions, and then reconstruct the pseudo-wave-functions to regain the oscillatory behavior of the all-electron valence wave functions near the atomic cores. We study the effect that this reconstruction has on the Compton profiles and their anisotropies. We find a decrease in the magnitude of the profiles at small wave vectors and in their anisotropies. These changes bring the theoretical predictions closer to experimental results. ͓S0163-1829͑98͒03628-5͔

Calculation of valence electron momentum densities using the projector augmented-wave method

“…[51]. As can be expected, for the LDA, the theoretical Compton profiles are higher at low momenta [48,16,51]. …”

“…Compton profiles or three-dimensional electron momentum densities have been calculated in the past with the DFT using, for example, the full-potential LAPW (FLAPW) method [8,9,10,11], localized basis sets [12,13], pseudowave functions [14], the orthogonalized plane-wave (OPW) method [15], the reconstruction of AE wave functions from pseudowave functions [16], the linear muffin-tin orbital method (LMTO) [17,18,19], the full-potential LMTO method [20], and the Korringa-Kohn-Rostoker (KKR) band-structure scheme [21,22,23]. The Hartree-Fock method has also been applied [12,24], and the GW approximation [9,10,25], as well as quantum Monte Carlo (QMC) methods [26,27] which go beyond the DFT and the LDA.…”

Defect identification in semiconductors with positron annihilation: Experiment and theory

“…Further, since the pseudo wave functions are ''softened,'' they do not represent the accurate all-electron wave functions even in the limit of a complete basis set. Techniques exist to reconstruct the allelectron wave functions from norm-conserving or ultrasoft wave functions (Meyer et al, 1995;Delaney, Králik, and Louie, 1998;Hetényi et al, 2001;Ishibashi, 2004) in a postprocessing fashion. Furthermore, the PAW method is especially useful since it involves a well-defined relation between soft pseudo wave functions jÉi represented in a plane-wave basis and the accurate all-electron wave functions jÉi (Blöchl, 1994),…”

Quantum Monte Carlo calculation of Compton profiles of solid lithium

“…To account for the correct oscillatory behavior of the valence wave functions, the valence orbitals are usually computed within traditional all-electron schemes (LAPW or LMTO) or, alternatively, the true valence wave functions are reconstructed from the pseudized orbitals [26,27]. On the other hand, several calculations in the literature have shown the feasibility of plane-wave calculations using the unscreened Coulomb potential for first-row elements [19,28,29].…”