| 706 |
|
respect to different coverages of butanethiol. To study the isotope |
| 707 |
|
effect in interfacial thermal conductance, deuterated UA-hexane is |
| 708 |
|
included as well. |
| 709 |
+ |
|
| 710 |
+ |
\begin{figure} |
| 711 |
+ |
\includegraphics[width=\linewidth]{coverage} |
| 712 |
+ |
\caption{Comparison of interfacial thermal conductivity ($G$) values |
| 713 |
+ |
for the Au-butanethiol/solvent interface with various UA models and |
| 714 |
+ |
different capping agent coverages at $\langle T\rangle\sim$200K |
| 715 |
+ |
using certain energy flux respectively.} |
| 716 |
+ |
\label{coverage} |
| 717 |
+ |
\end{figure} |
| 718 |
|
|
| 719 |
|
It turned out that with partial covered butanethiol on the Au(111) |
| 720 |
|
surface, the derivative definition for $G^\prime$ |
| 759 |
|
studies, even though eliminating C-H vibration samplings, still have |
| 760 |
|
C-C vibrational frequencies different from each other. However, these |
| 761 |
|
differences in the infrared range do not seem to produce an observable |
| 762 |
< |
difference for the results of $G$. [MAY NEED SPECTRA FIGURE] |
| 762 |
> |
difference for the results of $G$ (Figure \ref{uahxnua}). |
| 763 |
|
|
| 764 |
+ |
\begin{figure} |
| 765 |
+ |
\includegraphics[width=\linewidth]{uahxnua} |
| 766 |
+ |
\caption{Vibrational spectra obtained for normal (upper) and |
| 767 |
+ |
deuterated (lower) hexane in Au-butanethiol/hexane |
| 768 |
+ |
systems. Butanethiol spectra are shown as reference. Both hexane and |
| 769 |
+ |
butanethiol were using United-Atom models.} |
| 770 |
+ |
\label{uahxnua} |
| 771 |
+ |
\end{figure} |
| 772 |
+ |
|
| 773 |
|
Furthermore, results for rigid body toluene solvent, as well as other |
| 774 |
|
UA-hexane solvents, are reasonable within the general experimental |
| 775 |
|
ranges[CITATIONS]. This suggests that explicit hydrogen might not be a |
| 788 |
|
level. This becomes an offset for decreasing butanethiol molecules on |
| 789 |
|
its effect to the process of interfacial thermal transport. Thus, one |
| 790 |
|
can see a plateau of $G$ vs. butanethiol coverage in our results. |
| 773 |
– |
|
| 774 |
– |
\begin{figure} |
| 775 |
– |
\includegraphics[width=\linewidth]{coverage} |
| 776 |
– |
\caption{Comparison of interfacial thermal conductivity ($G$) values |
| 777 |
– |
for the Au-butanethiol/solvent interface with various UA models and |
| 778 |
– |
different capping agent coverages at $\langle T\rangle\sim$200K |
| 779 |
– |
using certain energy flux respectively.} |
| 780 |
– |
\label{coverage} |
| 781 |
– |
\end{figure} |
| 791 |
|
|
| 792 |
|
\subsection{Influence of Chosen Molecule Model on $G$} |
| 793 |
|
In addition to UA solvent/capping agent models, AA models are included |
| 864 |
|
temperatures. In comparison, once either the hexanes or the |
| 865 |
|
butanethiols are deuterated, one can see a significantly lower $G$ and |
| 866 |
|
$G^\prime$. In either of these cases, the C-H(D) vibrational overlap |
| 867 |
< |
between the solvent and the capping agent is removed. |
| 868 |
< |
[ NEED SPECTRA FIGURE] Conclusively, the |
| 869 |
< |
improperly treated C-H vibration in the AA model produced |
| 870 |
< |
over-predicted results accordingly. Compared to the AA model, the UA |
| 871 |
< |
model yields more reasonable results with higher computational |
| 863 |
< |
efficiency. |
| 867 |
> |
between the solvent and the capping agent is removed (Figure |
| 868 |
> |
\ref{aahxntln}). Conclusively, the improperly treated C-H vibration in |
| 869 |
> |
the AA model produced over-predicted results accordingly. Compared to |
| 870 |
> |
the AA model, the UA model yields more reasonable results with higher |
| 871 |
> |
computational efficiency. |
| 872 |
|
|
| 873 |
+ |
\begin{figure} |
| 874 |
+ |
\includegraphics[width=\linewidth]{aahxntln} |
| 875 |
+ |
\caption{Spectra obtained for All-Atom model Au-butanethil/solvent |
| 876 |
+ |
systems. When butanethiol is deuterated (lower left), its |
| 877 |
+ |
vibrational overlap with hexane would decrease significantly, |
| 878 |
+ |
compared with normal butanethiol (upper left). However, this |
| 879 |
+ |
dramatic change does not apply to toluene as much (right).} |
| 880 |
+ |
\label{aahxntln} |
| 881 |
+ |
\end{figure} |
| 882 |
+ |
|
| 883 |
|
However, for Au-butanethiol/toluene interfaces, having the AA |
| 884 |
|
butanethiol deuterated did not yield a significant change in the |
| 885 |
|
measurement results. Compared to the C-H vibrational overlap between |
