--- trunk/COonPt/COonPtAu.tex	2013/03/21 15:28:49	3887
+++ trunk/COonPt/COonPtAu.tex	2013/06/04 20:22:12	3890
@@ -4,6 +4,7 @@
 \usepackage{natbib}
 \usepackage{multirow}
 \usepackage{wrapfig}
+\usepackage{fixltx2e}
 %\mciteErrorOnUnknownfalse
 
 \usepackage[version=3]{mhchem}  % this is a great package for formatting chemical reactions
@@ -323,15 +324,74 @@ an effect on binding energies and binding site prefere
   \hline
   & Calculated & Experimental \\
   \hline
-  \multirow{2}{*}{\textbf{Pt-CO}} & \multirow{2}{*}{-1.9} & -1.4 \bibpunct{}{}{,}{n}{}{,}
+  \multirow{2}{*}{\textbf{Pt-CO}} & \multirow{2}{*}{-1.84} & -1.4 \bibpunct{}{}{,}{n}{}{,}
   (Ref. \protect\cite{Kelemen:1979}) \\
  & &  -1.9 \bibpunct{}{}{,}{n}{}{,} (Ref. \protect\cite{Yeo}) \\ \hline
   \textbf{Au-CO} & -0.39 & -0.40 \bibpunct{}{}{,}{n}{}{,}  (Ref. \protect\cite{TPDGold}) \\
   \hline
 \end{tabular}
 \label{tab:co_energies}
+\end{table}
+
+
+\subsection{Validation of forcefield selections}
+By calculating minimum energies for commensurate systems of 
+single and double layer Pt and Au systems with 0 and 50\% coverages 
+(arranged in a c(2x4) pattern), our forcefield selections were able to be 
+indirectly compared to results shown in the supporting information of Tao 
+{\it et al.} \cite{Tao:2010}. Five layer thick systems, displaying a 557 facet 
+were constructed, each composed of 480 metal atoms. Double layers systems 
+were constructed from six layer thick systems where an entire layer was 
+removed from both displayed facets to create a double step. By design, the 
+double step system also contains 480 atoms, five layers thick, so energy 
+comparisons between the arrangements can be made directly. The positions
+of the atoms were allowed to relax, along with the box sizes, before a
+minimum energy was calculated. Carbon monoxide, equivalent to 50\%
+coverage on one side of the metal system was added in a c(2x4) arrangement
+and again allowed to relax before a minimum energy was calculated.
+
+Energies for the various systems are displayed in Table ~\ref{tab:steps}. Examining
+the Pt systems first, it is apparent that the double layer system is slightly less stable
+then the original single step. However, upon addition of carbon monoxide, the 
+stability is reversed and the double layer system becomes more stable. This result
+is in agreement with DFT calculations in Tao {\it et al.}\cite{Tao:2010}, who also show
+that the addition of CO leads to a reversal in the most stable system. While our
+results agree qualitatively, quantitatively, they are approximately an order of magnitude
+different. Looking at additional stability per atom in kcal/mol, the DFT calculations suggest
+an increased stability of 0.1 kcal/mol per Pt atom, whereas we are seeing closer to a 0.4 kcal/mol
+increase in stability per Pt atom.
+
+The gold systems show a much smaller energy difference between the single and double
+systems, likely arising from their lower energy per atom values. Additionally, the weaker
+binding of CO to Au is evidenced by the much smaller energy change between the two systems,
+when compared to the Pt results. This limited change helps explain our lack of any reconstruction
+on the Au systems.
+
+
+%Table of single step double step calculations
+\begin{table}[H]
+\caption{Minimized single point energies of unit cell crystals displaying (S)ingle or (D)double steps. Systems are periodic along and perpendicular to the step-edge axes with a large vacuum above the displayed 557 facet. The relative energies are calculated as $E_{relative} = E_{system} - E_{M-557-S} - N_{CO}\Delta E_{CO-M}$ , where $E_{CO-M}$  is -1.84 eV for Pt-CO and -0.39 eV for Pt-CO. The addition of CO in a 50\% c(2x4) coverage acts as a stabilizing presence and suggests a driving force for the observed reconstruction on the highest coverage Pt system. All energies are in kcal/mol.}
+\centering
+\begin{tabular}{| c | c | c | c | c | c |}
+\hline
+\textbf{Step} & \textbf{N}\textsubscript{M} & \textbf{N\textsubscript{CO}} & \textbf{Relative Energy} & \textbf{$\Delta$E/M} & \textbf{$\Delta$E/CO} \\
+\hline
+Pt(557)-S & 480 & 0 & 0 & 0 & - \\
+Pt(557)-D & 480 & 0 & 114.783 & 0.239 & -\\
+Pt(557)-S & 480 & 40 & -124.546 & -0.259 & -3.114\\
+Pt(557)-D & 480 & 44 & -34.953 & -0.073 & -0.794\\
+\hline
+\hline
+Au(557)-S & 480 & 0 & 0 & 0 & - \\
+Au(557)-D & 480 & 0 & 79.572 & 0.166 & - \\
+Au(557)-S & 480 & 40 & -157.199 & -0.327 & -3.930\\
+Au(557)-D & 480 & 44 & -123.297 & -0.257 & -2.802 \\
+\hline
+\end{tabular}
+\label{tab:steps}
 \end{table}
 
+
 \subsection{Pt(557) and Au(557) metal interfaces}
 Our Pt system is an orthorhombic periodic box of dimensions
 54.482~x~50.046~x~120.88~\AA~while our Au system has 
