Science Advances

Supplementary Materials

This PDF file includes:

  • Table S1. Fractional coordinates of the structure III (s-III) clathrate with cubic lattice (space group: P 4 3n, lattice constant: 13.431 Å) from vdW-DF2 DFT calculation.
  • Table S2. Average lengths of O–H covalent bond (dO–H) and hydrogen bond (dO…H) for different phases (ice XI, ice i, s-I, s-II, s-H, SGT, s-K, s-T, and s-III clathrates) based on vdW-DF2 DFT computation.
  • Table S3. Mass density (ρ) and lattice cohesive energy per water molecule (Elatt) for different phases (ice XI, ice i, s-I, s-II, s-H, SGT, s-K, s-T, and s-III clathrates) based on vdW-DF2 (DFT) optimization, and another independent optimization using the TIP4P/2005 water model (at zero temperature and zero pressure).
  • Fig. S1. Phonon dispersion for guest-free s-III ice clathrate based on vdW-DF2 DFT computation.
  • Fig. S2. Crystal structures (2 × 2 unit cells) of ice i, ice XI, and clathrates of s-T, s-I, s-II, s-K, SGT, and s-H phases (blue dash lines for hydrogen bonds, red for oxygen, and white for hydrogen).
  • Fig. S3. Lattice cohesive energies (Elatt) for structures ice XI, ice i, s-K, s-I, s-II, s- H, s-III, SGT, and s-T clathrates as a function of volume per water molecule.
  • Fig. S4. Computed Helmholtz energy (Asol) of the s-III clathrate based on the TIP4P/2005 potential, using the Einstein method, as a function of real-space cutoff distance rcutoff.

Download PDF

Files in this Data Supplement: