The normal modes of lattice vibrations of ice XI

Zhang, Peng; Wang, Zhe; Lu, Ying‐Bo; Ding, Zhengwen

doi:10.1038/srep29273

Cited by 25 publications

(24 citation statements)

References 30 publications

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“…The Raman scattering peaks, which correspond to the frequencies of vibrational normal modes at the gamma point caused by the interactions between photons and phonons, are restricted to the region near the Brillouin zone (BZ) center. The experimental INS data can be compared with the simulated PDOS curves, because the INS measurements collected the phonon signals throughout the whole BZ [25]. A comparison of the INS data ( [26]) and calculated PDOS of deuterated ice XVII is shown in figure 2 to manifest the validity of the simulation in this work.…”

Section: Resultsmentioning

confidence: 71%

Computational analysis of vibrational spectrum and hydrogen bonds of ice XVII

Zhu

Yuan

et al. 2019

New J. Phys.

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Based on first-principles density functional theory, we investigated the relationship between the vibrational normal modes and the spectrum of the newest laboratory-prepared ice phase, an empty clathrate hydrate structure from gas hydrate named ice XVII. A 48-molecule supercell was designed to mimic the hydrogen-disordered structure. Despite its much lower density than ice Ih, its phonon density of states shows features very similar to those of that phase. In our previous studies of ice Ic and ice XIV, we found two basic hydrogen bond vibrational modes in these hydrogen-ordered ice phases, which contribute two sharp hydrogen bond peaks in the translation region. In this study, we found that this rule also holds in the hydrogen-disordered phase ice XVII. A water molecule vibrating along its angle bisector possesses strong energy, because this vibrational mode involves oscillation against four bonded neighbors. In contrast, a water molecule vibrating perpendicular to its angle bisector has low energy because this mode involves only two of the molecule's hydrogen bonds. This is an evidence in hydrogen-disordered ice and strengthens our proposal that the existence of two basic hydrogen bond vibrational modes is a general rule among ice family. Figure 5. Smoothed probability density distribution of bond angles of ice XVII (blue) and ice Ih (black). Inset: Normal mode at 1647 cm −1 . This vibrational mode is mainly contributed by water molecules with large bond angles, which are highlighted in gold.

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Section: Resultsmentioning

confidence: 71%

Computational analysis of vibrational spectrum and hydrogen bonds of ice XVII

Zhu

Yuan

et al. 2019

New J. Phys.

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“…Compared with the insertion of PDOS, one can see a minor discrepancy due to phonon dispersion throughout the BZ as explained in our previous work. 28…”

Section: Results and Discussionmentioning

confidence: 99%

Computing Investigations of Molecular and Atomic Vibrations of Ice IX

et al. 2019

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The normal modes of ice IX were investigated using the CASTEP code package, which is based on density functional theory. We found that the translational modes could be divided into three categories: four-bond vibrations, which possessed the highest energy; two-bond vibrations, which possessed the medium energy; and cluster vibrations with the lowest energy. The former two categories represent monomers vibrating against neighbors and present as two distinct peaks in many ice phases recorded in inelastic neutron-scattering experiments. It is typically difficult to assign the molecular vibration peaks in the far infrared region. The method we developed to analyze the normal modes, especially in the translation band of ice IX, provided physical insights into the vibrational spectrum of ice.

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“…Using the CASTEP [27] code based on the first-principles density functional theory (DFT) method, the phonon density of states (PDOS) of ice II were calculated. We chose the RPBE [28] exchange-correlation functional of the generalized gradient approximation (GGA) according to our test, which produced a slight redshift in the translation band but had acceptable accuracy in the stretching band [29]. The energy threshold and self-consistent field tolerance were set as 1 × 10 −9 eV/atom for geometry optimization.…”

Section: Methodsmentioning

confidence: 99%

DFT Investigations of the Vibrational Spectra and Translational Modes of Ice II

et al. 2019

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The vibrational spectrum of ice II was investigated using the CASTEP code based on first-principles density functional theory (DFT). Based on good agreement with inelastic neutron scattering (INS), infrared (IR), and Raman experimental data, we discuss the translation, libration, bending, and stretching band using normal modes analysis method. In the translation band, we found that the four-bond and two-bond molecular vibration modes constitute three main peaks in accordance with INS ranging from 117 to 318 cm−1. We also discovered that the lower frequencies are cluster vibrations that may overlap with acoustic phonons. Whale et al. found in ice XV that some intramolecular vibrational modes include many isolated-molecule stretches of only one O–H bond, whereas the other O–H bond does not vibrate. This phenomenon is very common in ice II, and we attribute it to local tetrahedral deformation. The pathway of combining normal mode analysis with experimental spectra leads to scientific assignments.

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The normal modes of lattice vibrations of ice XI

Cited by 25 publications

References 30 publications

Computational analysis of vibrational spectrum and hydrogen bonds of ice XVII

Computational analysis of vibrational spectrum and hydrogen bonds of ice XVII

Computing Investigations of Molecular and Atomic Vibrations of Ice IX

DFT Investigations of the Vibrational Spectra and Translational Modes of Ice II

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