Second-generation charge-optimized many-body potential for $\text{Si}/{\text{SiO}}_2$ and amorphous silica

A second-generation dynamic charge transfer, many-body potential function is proposed for crystalline and amorphous silica, and for silicon. The potential is based on the first-generation charge-optimized many-body (COMB) potential for these materials. The materials fidelity of the proposed formalism is demonstrated for several crystalline silica polymorphs and amorphous silica. The correct order of most of the experimentally observed polymorphs of the oxide is obtained and a significant improvement is found for the mechanical properties over the predictions of the first-generation potential. Satisfactory agreement is obtained for predictions of structural properties and defect formation energies compared to experimental and first-principles computational values. This potential can be used in conjunction with recently developed COMB potentials for the $\text{Hf}/{\text{HfO}}_2$ systems.

Figure 1

The final relaxed structures of oxygen atoms adsorbed at the atop site, bridge site, and backbond site, from left to right, respectively, on a $2\times 1$ reconstructed Si (001) surface from (a) DFT-PBE calculations and (b) MD using the COMB10 potential. Larger atoms are Si and the smaller ones are O; atoms are color coded by the charges with the color bar indicating the charge values.

Figure 2

Snapshots of the Si and $\alpha$-quartz interfacial structure after force and energy minimization, viewing along (a) $⟨100⟩$ and (b) $⟨001⟩$ directions. Larger spheres are Si atoms, smaller ones are O atoms. The atoms are color coded by the coordination number with black and white being two and fourfold coordinated, respectively.

Figure 3

Snapshots of the Si and $\alpha$-quartz interfacial structure after equilibrating at 300 K for 20 ps, viewing along (a) $⟨100⟩$ and (b) $⟨001⟩$ directions. Larger spheres are Si atoms, smaller ones are O atoms. The atoms are color coded by the atomic charges with the charge values indicated by the color bar.

Figure 4

(Color online) The distribution of charges of Si (red crosses) and O (blue X’s) atoms across the $\text{Si}/\alpha$-quartz interface.