--- trunk/ssdePaper/nptSSD.tex 2004/02/04 18:51:43 1017 +++ trunk/ssdePaper/nptSSD.tex 2004/02/04 20:19:21 1019 @@ -209,8 +209,10 @@ cubic switching function at a cutoff radius. Under th Long-range dipole-dipole interactions were accounted for in this study by using either the reaction field method or by resorting to a simple -cubic switching function at a cutoff radius. Under the first method, -the magnitude of the reaction field acting on dipole $i$ is +cubic switching function at a cutoff radius. The reaction field +method was actually first used in Monte Carlo simulations of liquid +water.\cite{Barker73} Under this method, the magnitude of the reaction +field acting on dipole $i$ is \begin{equation} \mathcal{E}_{i} = \frac{2(\varepsilon_{s} - 1)}{2\varepsilon_{s} + 1} \frac{1}{r_{c}^{3}} \sum_{j\in{\mathcal{R}}} {\bf \mu}_{j} f(r_{ij})\ , @@ -891,7 +893,18 @@ respectively. radial location of the minima following the first solvation shell peak, and g$(r)$ is either g$_\text{OO}(r)$ or g$_\text{OH}(r)$ for calculation of the coordination number or hydrogen bonds per particle -respectively. +respectively. The number of hydrogen bonds stays relatively constant +across all of the models, but the coordination numbers of SSD/E and +SSD/RF show an improvement over SSD1. This improvement is primarily +due to the widening of the first solvation shell peak, allowing the +first minima to push outward. Comparing the coordination number with +the number of hydrogen bonds can lead to more insight into the +structural character of the liquid. Because of the near identical +values for SSD1, it appears to be a little too exclusive, in that all +molecules in the first solvation shell are involved in forming ideal +hydrogen bonds. The differing numbers for the newly parameterized +models indicate the allowance of more fluid configurations in addition +to the formation of an acceptable number of ideal hydrogen bonds. The time constants for the self orientational autocorrelation function are also displayed in Table \ref{liquidproperties}. The dipolar @@ -906,7 +919,12 @@ performed at the STP density for each of the respectiv vector can be calculated from an exponential fit in the long-time regime ($t > \tau_l^\mu$).\cite{Rothschild84} Calculation of these time constants were averaged from five detailed NVE simulations -performed at the STP density for each of the respective models. +performed at the STP density for each of the respective models. Again, +SSD/E and SSD/RF show improved behavior over SSD1 both with and +without an active reaction field. Numbers published from the original +SSD dynamics studies appear closer to the experimental values, and we +attribute this discrepancy to the implimentation of an Ewald sum +versus a reaction field. \subsection{Additional Observations}