This paper analyzes the structural, energetic and mechanical properties of carbon dioxide hydrate clathrates calculated using finite cluster and periodic ab initio density-functional theory methodologies. Intermolecular interactions are described by the exchange-hole dipole moment method. The stability, gas saturation energetics, guest-host interactions, cage deformations, vibrational frequenci...

Four new compounds Cs17.4(1)Na60.6(1)Sn138 (1), Rb19.1(1)Na58.9(1)Sn138 (2), K21.3(1)Na56.7(1)Sn138 (3), and Rb20Na12Sn100 (4) were synthesized by fusion of the corresponding elements. The structures were determined by single-crystal X-ray diffraction. Compounds 1-3 are isostructural and crystallize in a new structure type (rhombohedral, R3m, Z = 1, a = 12.4567(9) A, c = 51.533(3) A for 1; a = ...

The lattice constants of hydrogenated and deuterated CH4-, CO2-, Xe- (clathrate structure type I) and N2-hydrates (clathrate structure type II) from 10 K up to the stability limit were established in neutron- and synchrotron diffraction experiments and were used to derive the related thermal expansivities. The following results emerge from this analysis: (1) The differences of expansivities of ...

The synthesis and structural, chemical, and transport properties of a new clathrate compound with elemental composition Cs8Zn4Sn42 is reported. This compound is cubic with space group Pm3hn and a lattice parameter of 12.1226(19) Å. Single-crystal X-ray diffraction and structural refinement indicate that Cs atoms reside in the polyhedral cavities formed by the tetrahedrally bonded network of Zn ...

The nature of the inclusions in ten clathrate complexes of Dianin's compound have been investigated by the use of electron-density difference maps. The guest species are the first eight straight-chain carboxylic acids, formic to octanoic, a branched-chain acid (dimethylacetic acid) and trifluoroacetic acid. The point-group symmetry of the clathrate cavity, 3, is satisfied by partial occupation ...

In the title compound, C(6)H(7)ClN(+)·BF(4) (-)·C(12)H(24)O(6), the complete cation is generated by crystallographic mirror symmetry, with two C atoms and the N and Cl atoms lying on the mirror plane. The complete crown ether is also generated by mirror symmetry, as is the anion (in which the B and two F atoms lie on the mirror plane). The -NH(3) (+) group of the cation inserts into the crown-e...

Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Majo...

We have calculated the room temperature thermal conductivity in semiconductor germanium clathrates using statistical linear-response theory and an equilibrium molecular dynamics (MD) approach. A key step in our study is to compute a realistic heat-current J (t) and a corresponding auto-correlation function < J (t) J (0) >. To ensure convergence of our results and to minimize statistical fluctua...

We have carried out Raman spectroscopy and X-ray diffraction to 60 GPa of the 1 : 1 H20: H 2 clathrate hydrate, which has water molecules in an arrangement similar to pure ices I c and VII. The pressure dependence of both the Vo_ n frequency and the intermolecular distance do_m..o is significantly larger than in pure ice: unexpectedly, both dependencies can be mapped onto those of pure ice by d...

Abstract. The variations of ?O2/N2 and ?Ar/N2 in the Dome Fuji ice core were measured from 112 m (bubbly ice) to 2001 (clathrate hydrate ice). Our method, combined with low storage temperature samples (?50 ?C), successfully excludes post-coring gas-loss fractionation signals our data. From bubbly middle bubble–clathrate transition zone (BCTZ) (112–800 m) below BCTZ (&gt;1200 m), data exhibit or...