Gaussian charge-transfer charge distributions for non-self-consistent electronic structure calculations

We present a scheme to construct charge densities for non-self-consistent density functional theory calculations. Effects of charge transfer are added onto the density of overlapping atomic charge densities by means of charge-neutral spherical atom-centered Gaussian charge distributions that have been fitted to the self-consistent charge density in amorphous model systems. The electronic structure and forces obtained from non-self-consistent calculations using these a priori constructed charge densities are in good agreement with fully self-consistent calculations, and the Gaussian charge-transfer charges exhibit a satisfactory transferability between compounds of similar stochiometry but different geometry.

Figure 1

Band structure and DOS of $\alpha$-Si${}_3$N${}_4$ calculated self-consistently (solid lines) and non-self-consistently using CTCs from a-Si${}_3$N${}_4$ (dotted lines).

Figure 2

Band structure and DOS of $\beta$-Si${}_3$N${}_4$ calculated self-consistently (solid lines) and non-self-consistently using CTCs from a-Si${}_3$N${}_4$ (dotted lines).

Figure 3

Band structure and DOS of $\gamma$-Si${}_3$N${}_4$ calculated self-consistently (solid lines) and non-self-consistently using CTCs from a-Si${}_3$N${}_4$ (dotted lines).

Figure 4

Structure factor of a-Si${}_3$N${}_4$ (solid line) and $\alpha$-Si${}_3$N${}_4$ (shaded area).

Figure 5

Spherical Gaussian charge-transfer charges for Si (solid line) and N (dashed line), fitted to the self-consistent charge density of a-Si${}_3$N${}_4$. Both charge distributions are centered at $r=0$.

Figure 6

Spherical Gaussian charge-transfer charge density (e/Å${}^3$) in a [001] plane in $\beta$-Si${}_3$N${}_4$. Isolines are drawn at $-$0.075, $-$0.05, 0.0, 0.1, and 0.2 eV/Å${}^3$.

Figure 7

Charge density difference (e/Å${}^3$) ${\rho }_{\mathrm{sc}}-{\rho }_{\mathrm{at}}$, the self-consistent charge density minus the sum of overlapping atomic charge densities in a [001] plane in $\beta$-Si${}_3$N${}_4$. Isolines are drawn at $-$0.15, $-$0.1, 0.0, 0.1, 0.2, and 0.3 e/Å${}^3$.

Figure 8

Charge density difference (e/Å${}^3$) ${\rho }_{\mathrm{sc}}-{\rho }_{\mathrm{at}}-{\rho }_{\mathrm{ctc}}$, the self-consistent charge density minus the sum of overlapping atomic charge densities and CTCs in a [001] plane in $\beta$-Si${}_3$N${}_4$. Isolines are drawn at $-$0.2, $-$0.1, $-$0.03, 0.0, 0.05, 0.1, and 0.2 e/Å${}^3$.

Figure 9

Band structure and DOS of $\alpha$-SiO${}_2$: calculated self-consistently (solid lines) and non-self-consistently using CTCs from a-SiO${}_2$ (dotted lines).

Figure 10

Band structure and DOS of GaAs: calculated self-consistently (solid lines) and non-self-consistently using CTCs from a-GaAs (dotted lines).

Figure 11

Band structure and DOS of AlAs: calculated self-consistently (solid lines) and non-self-consistently using CTCs from a-AlAs (dotted lines).