Ab initio investigation into the elasticity of ultrahigh-pressure phases of SiO2

In search of new reconstructions of (001) α-quartz surface: a first principles study

“…The computed Bader charges correlate well with the analysis of Si and O electronegativities 33 and previously reported results (from 3.26e to 3.33e and from À1.63 to À1.67 for Si and O, respectively). 34,35 For a-SiO 2 , the computed PBE band gap is found to be 5.71 eV, and it is, as expected, smaller compared to experimental values (8.9 AE 0.2 eV for amorphous SiO 2 (ref. 36)), but it is comparable with other theoretical studies (from about 5.6 eV for local density approximation or PBE to 9.4 eV for GW).…”

Computational searches for crystal structures of dioxides of group 14 elements (CO2, SiO2, GeO2) under ultrahigh pressure

“…Previous theoretical studies have successfully reproduced properties of known crystal phases and proposed unidentied crystal structures of AO 2 (A ¼ C, Si, or Ge) under ultrahigh pressure. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] These theoretical predictions were made by stochastic trials including genetic algorithms, or by geometry optimization or MD simulation starting from a known structure or an intuitive initial guess. Since a stable structure in an ultrahigh pressure environment might be completely different from that under normal pressure, especially in the case of CO 2 , it is not easy to comprehensively collect all polymorphs of AO 2 .…”