Point Group 2 C2 Materials

General Static dielectric tensor Dissipation factor Elastic stiffness tensor Piezoelectric tensor Elastooptic tensor 

Dmitriev, G.G. Gurzadyan, D.N. Nikogosyan 4.24 Handbook of Nonlinear Optical Crystals, 2nd edn. (Springer, Berlin, Heidelberg 1997) 

McCurdy Second and Higher Or- 4.29 der Elastic Constants, Landolt-Bbrnstein, New Series 111/29, ed. by D.F. Nelson, 0. Madelung (Springer, 

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Table 4.4-21 Monoclinic, point group 2 (C2) materials, cont.

The best cathode material is NiPSj. No parameter expansion is observed during intercalation. The space group is C2/m. Lithium can occupy 2d or 4h octahedral sites or 4i and 8j tetrahedral sites. A localization in the octahedral voids is consistent with the following points (i) the Li-S distances (254 pm) are very similar to those found in LiTiSj (256 pm), where lithium is also in octahedral sites (ii) the number of available sites leads to the limit formula Lii jNiPSj, which is experimentally observed (iii) the small size of the tetrahedral voids will lead to a parameter expansion. On the discharge curve (Fig. 2) there is a small but reproducible discontinuity at x = 0.5. It is related to the filling of the first type of octahedral site (2d sites). 

As shown in the previous section, molecular symmetry largely affects the spectroscopic features of the molecular materials. The oligothiophenes have a well-defined molecular symmetry and belong to the point group of either C2/, or C2v according to whether the molecule has an even or odd number of thiophene units, respectively (refer to Figure 8.14). This molecular symmetry is retained almost completely in the crystals of both the neutral and doped forms (see Section 3.2). 

Fig. 2 A Port is a compound with two pairs of four Particles. Here, one parr of three points is shown to illustrate this 2D example. Ports are attached to any other Compound, most commonly anchored to a Particle where a chemical bond should exist Compound Cl is a methyl group with a Port anchored to the carbon atom. C2 is a methylene bridge already connected to a hydroxyl group. Cl and C2 are then attached using the equivalence relation described in Eq. (2) to create C3, an ethanol molecule. By default, a Bond is created between the two anchoring carbons. Adapted with permission from Fig. 2 in Sallai, J. et al. (2013) Web- and Cloud-based Software Infrastructure for Materials Design. Procedia Computer Science Elsevier...

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