Raman and IR Spectra of Ice Ih and Ice XI with an Assessment of DFT Methods

Liu, Yuan; Ojamäe, Lars

doi:10.1021/acs.jpcb.6b07001

Cited by 20 publications

(25 citation statements)

References 99 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By fitting the lattice energy versus volume curve with the Birch-Murnaghan equation (33), the equilibrium volume, average distance of the nearest O-O atoms, mass density, lattice energy, and bulk modulus of each ice polymorph are computed ( Table 2). Compared with the experimental data for ice XI and MTN ice (34)(35)(36), the computed mass densities are underestimated by 2.7 and 3.1%, respectively. The average O-O distance of the nearest water molecules is overestimated by 1.2% for ice XI and 1.0% for MTN.…”

Section: Resultsmentioning

confidence: 75%

An ultralow-density porous ice with the largest internal cavity identified in the water phase diagram

Liu

Huang

Zhu

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

The recent back-to-back findings of low-density porous ice XVI and XVII have rekindled the century-old field of the solid-state physics and chemistry of water. Experimentally, both ice XVI and XVII crystals can be produced by extracting guest atoms or molecules enclosed in the cavities of preformed ice clathrate hydrates. Herein, we examine more than 200 hypothetical low-density porous ices whose structures were generated according to a database of zeolite structures. Hitherto unreported porous EMT ice, named according to zeolite nomenclature, is identified to have an extremely low density of 0.5 g/cm 3 and the largest internal cavity (7.88 Å in average radius). The EMT ice can be viewed as dumbbell-shaped motifs in a hexagonal close-packed structure. Our first-principles computations and molecular dynamics simulations confirm that the EMT ice is stable under negative pressures and exhibits higher thermal stability than other ultralow-density ices. If all cavities are fully occupied by hydrogen molecules, the EMT ice hydrate can easily outperform the record hydrogen storage capacity of 5.3 wt % achieved with sII hydrogen hydrate. Most importantly, in the reconstructed temperaturepressure (T-P) phase diagram of water, the EMT ice is located at deeply negative pressure regions below ice XVI and at higher temperature regions next to FAU. Last, the phonon spectra of empty-sII, FAU, EMT, and other zeolite-like ice structures are computed by using the dispersion corrected vdW-DF2 functional. Compared with those of ice XI (0.93 g/cm 3 ), both the bending and stretching vibrational modes of the EMT ice are blue-shifted due to their weaker hydrogen bonds. porous ice | ultralow density | EMT ice | reconstructed temperaturepressure phase diagram | record hydrogen storage capacity W ater is a unique form of matter with many intriguing properties. One such physical property is its wide variety of stable and metastable crystal structures. To date, 18 different crystalline ice phases have been established experimentally (1-3). Many more ice phases ranging from 1D to 3D have been predicted from computer simulations (4-10). Another known ice form is ice clathrate hydrates with large internal cavities that can host guest molecules. Clathrate natural gas hydrates have received considerable attention because they are an enormous energy source on Earth. Indeed, the amount of carbon in natural gas hydrates is estimated to be at least twice that in all other fossil energies combined (11). Clathrate hydrogen hydrates have also received growing attention as they are a renewable and carbon-free energy source (12).In previous computer simulation studies, guest-free clathrate hydrates of type sII were independently predicted to be a stable phase at negative pressures by Jacobson et al. (13), Conde et al. (14), and Huang et al. (8). Remarkably, the guest-free clathrate hydrate of type sII was recently produced in the laboratory by Falenty et al. (2) by pumping off guest Ne atoms from the cavities of sII clathrate hydrate, confirming earlier ...

show abstract

Section: Resultsmentioning

confidence: 75%

An ultralow-density porous ice with the largest internal cavity identified in the water phase diagram

Liu

Huang

Zhu

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…This differs from the water clusters with different kinds of H-bonds (being revealed by the therein separated sub-spectra), and there is thus only one kind of H-bond in ice. 5 This observation provides an illustration to the historic debate on the existence of two kinds of H-bond in ice. [120][121][122] Figure 5.7.…”

mentioning

confidence: 84%

“…5 In each phase, the arrangements of oxygen atoms are long-2 range ordered in a specific symmetry with the hydrogen atoms arranged around the oxygen atoms following the ice rules. 42 Some of the ice phases are protondisordered (Ih, 43 Ic, 44 III, 45 IV, 46 V, 47 VI, 48 VII, 49 XII, 50 and XVI 51 ) and the others are proton-ordered (II, 52 VIII, 53 IX, 54 X, 55 XI, 56 XIII, 57 XIV, 57 and XV 58 ).…”

Section: Ice Ih and Ice XImentioning

confidence: 99%

“…To clarify the relation between the planetary formation and ice XI, the identification of ice Ih and ice XI should be carried out through IR and Raman spectroscopic investigations. 5 …”

Section: Ice Ih and Ice XI (Paper V)mentioning

confidence: 99%

“…In this thesis H-bonded systems (natural gas hydrates, [1][2][3] water clusters, 4 and crystal ice 5 ) are studied by density functional theory (DFT) computations.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Theoretical Studies of Natural Gas Hydrates and H-bonded Clusters and Crystals

Liu¹

Self Cite

View full text Add to dashboard Cite

In this thesis H-bonded systems (natural gas hydrates, water clusters, and crystal ice) are studied by density functional theory (DFT) computations.Natural gas hydrates (NGHs) play an important role in energy and environmental fields: NGHs are considered as a promising backup energy resource in the near-future due to their tremendous carbon content; improper exploration of NGHs could induce geological disasters and aggravate the greenhouse effect. In addition, many technologies based on gas hydrates are being applied and developed. The thermodynamic stabilities of various water cavities in different clathrate crystalline phases occupied by hydrocarbon gas molecules are studied by dispersion-corrected hybrid functionals. The Raman spectra of C-C and C-H stretching vibrations of hydrocarbon molecules in various water cavities in the solid state are derived. The trends of C-H stretching vibrational frequencies are found to follow the prediction by the "loose cage ─ tight cage" model. In addition, the trends and origins of 13 C NMR chemical shifts of hydrocarbon molecules in various NGHs are presented. These theoretical results will enlarge the database of C-C and C-H stretching vibrational frequencies and 13 C NMR parameters of hydrocarbon molecules in NGHs, and provide valuable information to help identify the types of clathrate phases and varieties of guest molecules included in NGHs samples taken from natural sites.The behavior of water clusters may help to understand the properties of its liquid and solid states. The thermodynamic stabilities and IR spectra of a small-, medium-, and large-sized water cluster are studied in this work. After full optimization of (H 2 O) 20,54,100 using the hybrid functional B3LYP, the electronic energies, zero-point energies, internal energies, enthalpies, entropies, and Gibbs free energies of the water clusters are computed. The OH stretching vibrational IR spectra of (H 2 O) 20,54,100 are also presented and split into sub-spectra for different H-bond types based on the specific contributions from each group. It is found that the OH stretching vibrational frequencies of water are sensitive to the conformations of the H-bonds and the vibrations of the H-bonds belonging to different types are located in separated regions in the IR spectra. Thus, the spectroscopic fingerprints will reflect the H-bond topology of the water molecules in a water cluster.Ice XI has been suggested to be involved in the process of planetary formation as a considerable electric field might be formed from the ferroelectric ice XI in space. IR and Raman spectroscopic technology can be directly used to identify the occurrence of ferroelectric ice XI in laboratory or extraterrestrial settings. Due to the difficulty for DFT to describe non-covalent systems, the performance of 16 different DFT methods applied on the ice Ih, VIII, IX, and XI crystal phases are assessed. Based on the computational accuracy and cost, the II IR and Raman spectra of ice Ih and XI are derived and compared. The librational vib...

show abstract