Charge optimized many-body potential for the $\mathrm{Si}∕{\mathrm{SiO}}_2$ system

A dynamic-charge, many-body potential for the $\mathrm{Si}∕{\mathrm{SiO}}_2$ system, based on an extended Tersoff potential for semiconductors, is proposed and implemented. The validity of the potential function is tested for both pure silicon and for five polymorphs of silica, for which good agreement is found between the calculated and experimental structural parameters and energies. The dynamic charge transfer intrinsic to the potential function allows the interface properties to be captured automatically, as demonstrated for the silicon/$\beta$-cristobalite interface.

Figure 1

Cohesive energies as a function of Si charge for interpenetrating Si fcc sublattices with equal and opposite charges at different values of isotropic strain using Yasu96 potential.

Figure 2

The distribution of charges on Si atoms in Si as determined from the Yasukawa potential becomes broader with increasing temperature.

Figure 3

(Color online) Lattice constants for silicon as a function of temperature predicted by COMB at zero pressure (open circles), as well as the values obtained by well-known Tersoff (stars) and Stillinger-Weber (open triangles) potential models, and comparing with experimental results (filled diamonds).

Figure 4

The potential energies as a function Si charge by COMB06 (solid line), and comparing with Yasu03 (dashed line) for the uniform charge case.

Figure 5

The charge distribution on the Si ions in $\alpha$-quartz for three different times of an MD run shows the development of unphysical $\mathrm{Si}\text{−}\mathrm{Si}$ charge dipoles by Yasu96.

Figure 6

(Color online) (a) Cohesive energies as a function of Si charge for $\alpha$-quartz system (solid lines), as well as isotropic compressive strain (filled circles) and tensile strain (open circles) by Yasu96; (b) Minimum energies (open circles) and corresponding Si charges (filled squares) as a function of isotropic strain by Yasu96. (c) Cohesive energies as a function of Si charge for $\alpha$-quartz system (solid lines), as well as isotropic compressive strain (filled circles) and tensile strain (open circles) by Yasu03.

Figure 7

The charge distribution on the Si ions in $\alpha$-quartz for three different times of an MD run shows the charge divergence by Yasu03.

Figure 8

(Color online) The potential energies as a function in the charge space for $\alpha$-$Q$. Horizontal axis is the charge for oxygen and vertical for silicon by Yasu03.

Figure 9

(Color online) The charge distribution of $\mathrm{Si}∕\beta \text{−}C$ interface for both Si and O (open symbols) along $x$ axis with local charge correction terms (solid lines), as well as without charge correction terms (dashed lines) by COMB06 potential.