Next-nearest neighbor molecule

This region has been divided into two subphases, L and S. The L phase differs from the L2 phase in the direction of tilt. Molecules tilt toward their nearest neighbors in L2 and toward next nearest neighbors in L (a smectic F phase). The S phase comprises the higher-ir and lower-T part of L2. This phase is characterized by smectic H or a tilted herringbone structure and there are two molecules (of different orientation) in the unit cell. Another phase having a different tilt direction, L, can appear between the L2 and L 2 phases. A new phase has been identified in the L 2 domain. It is probably a smectic L structure of different azimuthal tilt than L2 [185]. 

In water at room temperature some molecules have more than four nearest neighbors, but at any moment the majority have four neighbors, as in ice. If the molecules tend to have a tetrahedral arrangement like that of ice, the average distance between next-nearest neighbors would be... 

Fig. 20. The structure of ice Molecules numbered 8, 7, 6 are in contact with 5, while molecules 5, 4, 3, 2 arc in contact with 1. Molecules 2, 3, 4 are among the next-nearest neighbors of 5, while molecules 0, 7, 8 are among the next-nearest neighbors of 1. [Diagram taken from E. J. W. Verivey, Rec. trav. chim. 60, 893 (1941).]...

In Chapter 3, in discussing water near its freezing point, we took the point of view that at any moment the liquid contains many groups of molecules that have a local order similar to that of ice. In Fig. 20 the molecules numbered 2, 3, 4, 5 are nearest neighbors of molecule 1, while molecules 6, 7, 8 are neighbors of 5, and consequently arc next-nearest neighbors of 1. To be definite, let us identify the molecules 2, 3, 4, 5 with the outer tetrahedra of Fig. 19, and let us suppose that the protons... 

Our model for the adsorption of water on silicates was developed for a system with few if any interlayer cations. However, it strongly resembles the model proposed by Mamy (12.) for smectites with monovalent interlayer cations. The presence of divalent interlayer cations, as shown by studies of smectites and vermiculites, should result in a strong structuring of their primary hydration sphere and probably the next nearest neighbor water molecules as well. If the concentration of the divalent cations is low, then the water in interlayer space between the divalent cations will correspond to the present model. On the other hand, if the concentration of divalent cations approaches the number of ditrigonal sites, this model will not be applicable. Such a situation would only be found in concentrated electrolyte solutions. 

The most direct source of structural information, the diffraction studies, provides strong evidence for predominantly tetrahedral ordering of a molecule and its nearest neighbors, both in amorphous solid and liquid H2O. Other, weaker but still direct, structural evidence comes from the ratio of separations of nearest neighbor and next nearest neighbor 00 pairs in liquid water, the ubiquity of tetrahedral ordering in the several crystalline ices, and the statistical geometry of simulated water. 

Here act is the activation energy for a CO molecule with nn nearest-neigh-bors, nnn next-nearest-neighbors, and nnnn next-next-nearest-neighbors. 

The statistical thermodynamics analysis of -mers adsorption in a one-dimensional lattice provides an intuitive approach to linear molecules confined in quasi-one-dimensional nanotubes. More elaborated analytical solutions that incorporate nearest and next-nearest-neighbors between fc-mer s ends can be obtained by applying the mapping proposed in the present work. 

In some early applications [96] to ETs involving compounds with quin-one-like compounds Q, QA Q -A Q=, it was necessary to examine some data on the formation constants of the semiquinone QH, Q + QH2 — 2QH (The H is typically attached to an O or an N.) My impression, after looking at available data, was that the equilibrium constant was approximately the same, provided all three species had the same charge. Looking at the structures, one could see that every atom in a molecule on the left in this reaction corresponded to one on the right that had the same nearest and next nearest neighbor. I then looked at many examples of other pairs of compounds, which I termed conformal pairs and found that the total of heat of combustion of a pair was approximately the same as its conformal pair [97]. 

If we pass from the simple case of isolated to cumulated sulfur-sulfur bonds, then interactions between next nearest neighbors will influence the exact geometry of the molecules significantly (Figure 4). The simplest chemical compound containing cumulated sulfur-sulfur is elemental sulfur itself. 

Going from geometric models to possible real molecular models requires rather complicated calculations. In doing this, Tuinstra took into account the bond parameters from experimental data, repulsion of next nearest neighbors, volume effect, etc. Because of the great calculation time, only the conformations of molecules with between four and 14 atoms have been postulated, including the conformation of Si2. 

In the crystalline version of smectic B, there is positional as well as bond-orientational order, and this ordering is called hexagonal, as opposed to hexatic. In the tilted version of the hexatic smectic B, there are two different directions the tilt has been found to take with respect to the hexagonal bond orientation, namely toward nearest and toward next nearest neighbors, producing the two different smectics I and F (see Fig. 10-27). Similarly, there are two different tilted crystalline hexagonal phases, smectics J and G. Even in smectic crystals, the molecules retain freedom to rotate cooperatively about theii axes, hence smectic ciystals are not as solid as most simple crystals. Nature is wonderfully creative in contriving... 

Ethylidyne chemisorption also restructures the metal surface. This is shown for Rh(l 11) in Figure 2.27. The metal-metal distances expand for those rhodium atoms that bind to the carbon of the ethylidyne molecule located in the threefold site. This expansion forces the next nearest-neighbor rhodium atom more into the surface, which becomes corrugated as a result. The rhodium atom in the second layer directly underneath the ethylidyne binding site moves upward, closer to the organic molecule which is now bound more strongly to four instead of only three metal atoms. 

---