--- trunk/electrostaticMethodsPaper/SupportingInfo.tex 2006/03/23 15:46:45 2666 +++ trunk/electrostaticMethodsPaper/SupportingInfo.tex 2006/03/24 02:39:59 2667 @@ -148,13 +148,13 @@ based cutoffs really improves the results for these ne The pure cutoff ({\sc pc}) method performs poorly, again mirroring the observations in the main portion of this paper. In contrast to the combined values, however, the use of a switching function and group -based cutoffs really improves the results for these neutral water +based cutoffs greatly improves the results for these neutral water molecules. The group switched cutoff ({\sc gsc}) does not mimic the energetics of {\sc spme} as well as the {\sc sp} (with moderate damping) and {\sc sf} methods, but the dynamics are quite good. The -switching functions corrects discontinuities in the potential and +switching functions correct discontinuities in the potential and forces, leading to these improved results. Such improvements with the -use of a switching function has been recognized in previous +use of a switching function have been recognized in previous studies,\cite{Andrea83,Steinbach94} and this proves to be a useful tactic for stably incorporating local area electrostatic effects. @@ -168,7 +168,7 @@ A final note for the liquid water system, use of group show how incorporating some implicit properties of the surroundings (i.e. $\epsilon_\textrm{S}$) can improve the solvent depiction. -A final note for the liquid water system, use of group cutoffs and a +As a final note for the liquid water system, use of group cutoffs and a switching function leads to noticeable improvements in the {\sc sp} and {\sc sf} methods, primarily in directionality of the force and torque vectors (table \ref{tab:spceAng}). The {\sc sp} method shows @@ -286,7 +286,7 @@ expected, the energy gap agreement with {\sc spme} red Highly ordered systems are a difficult test for the pairwise methods in that they lack the periodicity term of the Ewald summation. As -expected, the energy gap agreement with {\sc spme} reduces for the +expected, the energy gap agreement with {\sc spme} is reduced for the {\sc sp} and {\sc sf} methods with parameters that were acceptable for the disordered liquid system. Moving to higher $R_\textrm{c}$ helps improve the agreement, though at an increase in computational cost. @@ -307,12 +307,10 @@ for the energy gap comparisons and the force and torqu A high temperature NaCl melt was tested to gauge the accuracy of the pairwise summation methods in a charged disordered system. The results -for the energy gap comparisons and the force and torque vector -magnitude comparisons are shown in table \ref{tab:melt}. The force -and torque vector directionality results are displayed separately in -table \ref{tab:meltAng}, where the effect of group-based cutoffs and -switching functions on the {\sc sp} and {\sc sf} potentials are -investigated. +for the energy gap comparisons and the force vector magnitude +comparisons are shown in table \ref{tab:melt}. The force vector +directionality results are displayed separately in table +\ref{tab:meltAng}. \begin{table}[htbp] \centering @@ -391,11 +389,9 @@ and torque vector magnitude comparisons are shown in t A 1000K NaCl crystal was used to investigate the accuracy of the pairwise summation methods in an ordered system of charged particles. The results for the energy gap comparisons and the force -and torque vector magnitude comparisons are shown in table -\ref{tab:salt}. The force and torque vector directionality results -are displayed separately in table \ref{tab:saltAng}, where the effect -of group-based cutoffs and switching functions on the {\sc sp} and -{\sc sf} potentials are investigated. +vector magnitude comparisons are shown in table \ref{tab:salt}. The +force vector directionality results are displayed separately in table +\ref{tab:saltAng}. \begin{table}[htbp] \centering @@ -476,14 +472,11 @@ expect given the good long-time dynamics results obser radius. The moderate electrostatic damping case is not as good as we would -expect given the good long-time dynamics results observed for this -system. Since the data tabulated in table \ref{tab:salt} and +expect given the long-time dynamics results observed for this +system. Since the data tabulated in tables \ref{tab:salt} and \ref{tab:saltAng} are a test of instantaneous dynamics, this indicates that good long-time dynamics comes in part at the expense of -short-time dynamics. Further indication of this comes from the full -power spectra shown in the main text. It appears as though a -distortion is introduced between 200 to 350 cm$^{-1}$ with increased -$\alpha$. +short-time dynamics. \section{\label{app:solnWeak}Weak NaCl Solution} @@ -504,9 +497,8 @@ GSC = Group Switched Cutoff, RF = Reaction Field (wher system. Tabulated results include $\Delta E$ values (top set), force vector magnitudes (middle set) and torque vector magnitudes (bottom set). PC = Pure Cutoff, SP = Shifted Potential, SF = Shifted Force, -GSC = Group Switched Cutoff, RF = Reaction Field (where $\varepsilon -\approx \infty$), GSSP = Group Switched Shifted Potential, and GSSF = -Group Switched Shifted Force.} +GSC = Group Switched Cutoff, and RF = Reaction Field (where $\varepsilon +\approx \infty$).} \begin{tabular}{@{} ccrrrrrr @{}} \\ \toprule @@ -615,8 +607,8 @@ torque vector magnitude comparisons are shown in table consisting of 40 ions in the 1000 SPC/E water solvent ($\approx$1.1 M). The results for the energy gap comparisons and the force and torque vector magnitude comparisons are shown in table -\ref{tab:solnWeak}. The force and torque vector directionality -results are displayed separately in table \ref{tab:solnWeakAng}, where +\ref{tab:solnStr}. The force and torque vector directionality +results are displayed separately in table \ref{tab:solnStrAng}, where the effect of group-based cutoffs and switching functions on the {\sc sp} and {\sc sf} potentials are investigated. @@ -714,7 +706,7 @@ configuration energy difference degrade to unusable le \end{table} The {\sc rf} method struggles with the jump in ionic strength. The -configuration energy difference degrade to unusable levels while the +configuration energy differences degrade to unusable levels while the forces and torques show a more modest reduction in the agreement with {\sc spme}. The {\sc rf} method was designed for homogeneous systems, and this attribute is apparent in these results. @@ -727,17 +719,17 @@ The final model system studied was 6 \AA\ sphere of Ar \section{\label{app:argon}Argon Sphere in Water} -The final model system studied was 6 \AA\ sphere of Argon solvated by -SPC/E water. The results for the energy gap comparisons and the force -and torque vector magnitude comparisons are shown in table -\ref{tab:solnWeak}. The force and torque vector directionality -results are displayed separately in table \ref{tab:solnWeakAng}, where +The final model system studied was a 6 \AA\ sphere of Argon solvated +by SPC/E water. The results for the energy gap comparisons and the +force and torque vector magnitude comparisons are shown in table +\ref{tab:argon}. The force and torque vector directionality +results are displayed separately in table \ref{tab:argonAng}, where the effect of group-based cutoffs and switching functions on the {\sc sp} and {\sc sf} potentials are investigated. \begin{table}[htbp] \centering - \caption{Regression results for the 6 \AA\ argon sphere in liquid + \caption{Regression results for the 6 \AA\ Argon sphere in liquid water system. Tabulated results include $\Delta E$ values (top set), force vector magnitudes (middle set) and torque vector magnitudes (bottom set). PC = Pure Cutoff, SP = Shifted Potential, SF = Shifted @@ -796,7 +788,7 @@ argon in liquid water system. PC = Pure Cutoff, SP = \centering \caption{Variance results from Gaussian fits to angular distributions of the force and torque vectors in the 6 \AA\ sphere of -argon in liquid water system. PC = Pure Cutoff, SP = Shifted +Argon in liquid water system. PC = Pure Cutoff, SP = Shifted Potential, SF = Shifted Force, GSC = Group Switched Cutoff, RF = Reaction Field (where $\varepsilon \approx \infty$), GSSP = Group Switched Shifted Potential, and GSSF = Group Switched Shifted Force.} @@ -833,11 +825,11 @@ This system appears not to show in any significant dev \label{tab:argonAng} \end{table} -This system appears not to show in any significant deviation in the -previously observed results. The {\sc sp} and {\sc sf} methods give -result qualities similar to those observed in section +This system does not appear to show any significant deviations from +the previously observed results. The {\sc sp} and {\sc sf} methods +have aggrements similar to those observed in section \ref{app:water}. The only significant difference is the improvement -for the configuration energy differences for the {\sc rf} method. This +in the configuration energy differences for the {\sc rf} method. This is surprising in that we are introducing an inhomogeneity to the system; however, this inhomogeneity is charge-neutral and does not result in charged cutoff spheres. The charge-neutrality of the cutoff