Angle distribution functions

How, if at all, is this model related to the one implied in the discussion of ice II and ice III — like local environments Note that the two models mentioned have an important common property, namely the presence of OOO angles which deviate considerably from 109.5° and which appear as distinct peaks in the OOO population versus angle distribution function. Now, placing an H2O molecule in an interstitial position in an ice I lattice also leads to the introduction of unusually small OOO angles ( 70°). We think it likely that any model of high density H20(as) must include 000 angles much smaller than 109.5°. 

Dihedral angle distribution functions for the various models are shown in figure 5. Models using the Bartell and BHS intramolecular potential functions show a clear bimodal distribution. The former shows a zero intensity near 9 = 0°. The latter shows a small non-zero intensity near 9 = 0°. The Haigh potential shows a distribution which may be described as lying somewhere between bimodal and monomodal. Both the WW and KK models show a monomodal function with a maximum near 9 = 0°, suggesting the most probable conformation is the planar conformation in the room temperature solid phase. The RDFs for these two models show well defined features which seem to be correlated with the monomodal S(9) exhibited by them. 

Figure 5. Dihedral angle distribution function for solid biphenyl at 300 K for models containing the intermolecular potential given by (a) Williams and Cox, and by (b) Kitaigorodskii.

Figure 8. Dihedral angle distribution function for liquid biphenyl at 400 K for the WW and...

Figure 18. Si-Si-Si angle distribution function for quartz for the same range of temperatures as shown in Figure 15 (top). The positions and widths of the two peaks that coalesce are shown as a function of temperature in the lower plots. The distribution functions were obtained from analysis of the RMC configurations.

Bond Length and Bond Angle Distribution Functions... 

Figure 20. Nearest-neighbor bond angle distribution functions for the time-averaged 3584-particle WCA liquid at p = 0.83. The figure shows the contributions from ordered regions (dotted line), disordered regions (dashed line), and the overall distribution (solid line). The horizontal scale is in degrees.

Figure 55. Bond angle distribution functions for the time-averaged 3584-particle WCA system, with each curve labeled by the corresponding value of p (a) solid region (h) coexistence region (c) liquid near freezing (4) liquid away from freezing.

Figure 9. Bond-angle distribution functions of liquid silicon for (a) bond lengths less than 2.51 A (2.40 A in the Car-Parrinello simulation) and (ft) bond lengths less than 3.22 A (3.12 A in the Car-Parrinello simulation). The thick line represents the TBMD result and the thin line is the result obtained by the Car-Parrinello method [47]). The arrow indicates the position of the tetrahedral angle. (From Ref. 33.)...

Fig. 1.18 Radial distribution functions (RDFs) and bond-angle distribution functions (BADFs) of four amorphous silicon structures shown in Fig. 1.17 (from Demkowicz and Argon (2005a) courtesy of the APS).

Fig. 1.21 Radial distribution functions and bond-angle distribution functions of the solid-like atom environments (a) and (b) and of the liquid-like environments (c) and (d)...

The results for the C71 chains also show that the performance of off-lattice simulations must be assessed by looking at all possible aspects of the simulation. Often used criteria, such as internal energy variation, torsional angle distribution function, and radial distribution function [38, 39,45] do not by themselves provide reliable performance indicators. 

---