| 508 |
|
200 & 266 & No & 0.672 & -0.96 & 102() & 80.0() \\ |
| 509 |
|
& 200 & Yes & 0.694 & 1.92 & 129() & 87.3() \\ |
| 510 |
|
& & Yes & 0.672 & 1.93 & 131() & 77.5() \\ |
| 511 |
< |
|
| 511 |
> |
& & No & 0.688 & 0.96 & 125() & 90.2() \\ |
| 512 |
> |
& & & & 1.91 & 139() & 101() \\ |
| 513 |
> |
& & & & 2.83 & 141() & 89.9() \\ |
| 514 |
|
& 166 & Yes & 0.679 & 0.97 & 115() & 69.3() \\ |
| 515 |
< |
& & Yes & 0.679 & 1.94 & 125() & 87.1() \\ |
| 516 |
< |
|
| 517 |
< |
250 & 200 & No & 0.560 & 0.96 & 81.8() & 67.0() \\ |
| 518 |
< |
|
| 515 |
> |
& & & & 1.94 & 125() & 87.1() \\ |
| 516 |
> |
& & No & 0.681 & 0.97 & 141() & 77.7() \\ |
| 517 |
> |
& & & & 1.92 & 138() & 98.9() \\ |
| 518 |
> |
\hline |
| 519 |
> |
250 & 200 & No & 0.560 & 0.96 & 74.8() & 61.8() \\ |
| 520 |
> |
& & & & -0.95 & 49.4() & 45.7() \\ |
| 521 |
|
& 166 & Yes & 0.570 & 0.98 & 79.0() & 62.9() \\ |
| 522 |
< |
|
| 523 |
< |
& & No & 0.569 & 1.44 & 76.2() & 64.8() \\ |
| 524 |
< |
|
| 522 |
> |
& & No & 0.569 & 0.97 & 80.3() & 67.1() \\ |
| 523 |
> |
& & & & 1.44 & 76.2() & 64.8() \\ |
| 524 |
> |
& & & & -0.95 & 56.4() & 54.4() \\ |
| 525 |
> |
& & & & -1.85 & 47.8() & 53.5() \\ |
| 526 |
|
\hline\hline |
| 527 |
|
\end{tabular} |
| 528 |
|
\label{AuThiolHexaneUA} |
| 688 |
|
its effect to the process of interfacial thermal transport. Thus, one |
| 689 |
|
can see a plateau of $G$ vs. butanethiol coverage in our results. |
| 690 |
|
|
| 691 |
< |
[NEED ERROR ESTIMATE, CONVERT TO FIGURE] |
| 692 |
< |
\begin{table*} |
| 693 |
< |
\begin{minipage}{\linewidth} |
| 694 |
< |
\begin{center} |
| 695 |
< |
\caption{Computed interfacial thermal conductivity ($G$) values |
| 696 |
< |
for the Au-butanethiol/solvent interface with various UA |
| 697 |
< |
models and different capping agent coverages at $\langle |
| 698 |
< |
T\rangle\sim$200K using certain energy flux respectively.} |
| 699 |
< |
|
| 695 |
< |
\begin{tabular}{cccc} |
| 696 |
< |
\hline\hline |
| 697 |
< |
Thiol & \multicolumn{3}{c}{$G$(MW/m$^2$/K)} \\ |
| 698 |
< |
coverage (\%) & hexane & hexane(D) & toluene \\ |
| 699 |
< |
\hline |
| 700 |
< |
0.0 & 46.5() & 43.9() & 70.1() \\ |
| 701 |
< |
25.0 & 151() & 153() & 249() \\ |
| 702 |
< |
50.0 & 172() & 182() & 214() \\ |
| 703 |
< |
75.0 & 242() & 229() & 244() \\ |
| 704 |
< |
88.9 & 178() & - & - \\ |
| 705 |
< |
100.0 & 137() & 153() & 187() \\ |
| 706 |
< |
\hline\hline |
| 707 |
< |
\end{tabular} |
| 708 |
< |
\label{tlnUhxnUhxnD} |
| 709 |
< |
\end{center} |
| 710 |
< |
\end{minipage} |
| 711 |
< |
\end{table*} |
| 691 |
> |
[NEED ERROR ESTIMATE] |
| 692 |
> |
\begin{figure} |
| 693 |
> |
\includegraphics[width=\linewidth]{coverage} |
| 694 |
> |
\caption{Comparison of interfacial thermal conductivity ($G$) values |
| 695 |
> |
for the Au-butanethiol/solvent interface with various UA models and |
| 696 |
> |
different capping agent coverages at $\langle T\rangle\sim$200K |
| 697 |
> |
using certain energy flux respectively.} |
| 698 |
> |
\label{coverage} |
| 699 |
> |
\end{figure} |
| 700 |
|
|
| 701 |
|
\subsection{Influence of Chosen Molecule Model on $G$} |
| 702 |
|
[MAY COMBINE W MECHANISM STUDY] |
| 717 |
|
\caption{Computed interfacial thermal conductivity ($G$ and |
| 718 |
|
$G^\prime$) values for interfaces using various models for |
| 719 |
|
solvent and capping agent (or without capping agent) at |
| 720 |
< |
$\langle T\rangle\sim$200K.} |
| 720 |
> |
$\langle T\rangle\sim$200K. (D stands for deuterated solvent |
| 721 |
> |
or capping agent molecules; ``Avg.'' denotes results that are |
| 722 |
> |
averages of several simulations.)} |
| 723 |
|
|
| 724 |
|
\begin{tabular}{ccccc} |
| 725 |
|
\hline\hline |
| 727 |
|
(or bare surface) & model & (GW/m$^2$) & |
| 728 |
|
\multicolumn{2}{c}{(MW/m$^2$/K)} \\ |
| 729 |
|
\hline |
| 730 |
< |
UA & AA hexane & 1.94 & 135() & 129() \\ |
| 731 |
< |
& & 2.86 & 126() & 115() \\ |
| 732 |
< |
& AA toluene & 1.89 & 200() & 149() \\ |
| 733 |
< |
AA & UA hexane & 1.94 & 116() & 129() \\ |
| 734 |
< |
& AA hexane & 3.76 & 451() & 378() \\ |
| 735 |
< |
& & 4.71 & 432() & 334() \\ |
| 736 |
< |
& AA toluene & 3.79 & 487() & 290() \\ |
| 737 |
< |
AA(D) & UA hexane & 1.94 & 158() & 172() \\ |
| 738 |
< |
bare & AA hexane & 0.96 & 31.0() & 29.4() \\ |
| 730 |
> |
UA & UA hexane & Avg. & 131() & 86.5() \\ |
| 731 |
> |
& UA hexane(D) & 1.95 & 153() & 136() \\ |
| 732 |
> |
& AA hexane & 1.94 & 135() & 129() \\ |
| 733 |
> |
& & 2.86 & 126() & 115() \\ |
| 734 |
> |
& UA toluene & 1.96 & 187() & 151() \\ |
| 735 |
> |
& AA toluene & 1.89 & 200() & 149() \\ |
| 736 |
> |
\hline |
| 737 |
> |
AA & UA hexane & 1.94 & 116() & 129() \\ |
| 738 |
> |
& AA hexane & Avg. & 442() & 356() \\ |
| 739 |
> |
& AA hexane(D) & 1.93 & 222() & 234() \\ |
| 740 |
> |
& UA toluene & 1.98 & 125() & 96.5() \\ |
| 741 |
> |
& AA toluene & 3.79 & 487() & 290() \\ |
| 742 |
> |
\hline |
| 743 |
> |
AA(D) & UA hexane & 1.94 & 158() & 172() \\ |
| 744 |
> |
& AA hexane & 1.92 & 243() & 191() \\ |
| 745 |
> |
& AA toluene & 1.93 & 364() & 322() \\ |
| 746 |
> |
\hline |
| 747 |
> |
bare & UA hexane & Avg. & 46.5() & 49.4() \\ |
| 748 |
> |
& UA hexane(D) & 0.98 & 43.9() & 43.0() \\ |
| 749 |
> |
& AA hexane & 0.96 & 31.0() & 29.4() \\ |
| 750 |
> |
& UA toluene & 1.99 & 70.1() & 65.8() \\ |
| 751 |
|
\hline\hline |
| 752 |
|
\end{tabular} |
| 753 |
|
\label{modelTest} |
| 784 |
|
|
| 785 |
|
However, for Au-butanethiol/toluene interfaces, having the AA |
| 786 |
|
butanethiol deuterated did not yield a significant change in the |
| 787 |
< |
measurement results. |
| 788 |
< |
. , so extra degrees of freedom |
| 789 |
< |
such as the C-H vibrations could enhance heat exchange between these |
| 790 |
< |
two phases and result in a much higher conductivity. |
| 787 |
> |
measurement results. Compared to the C-H vibrational overlap between |
| 788 |
> |
hexane and butanethiol, both of which have alkyl chains, that overlap |
| 789 |
> |
between toluene and butanethiol is not so significant and thus does |
| 790 |
> |
not have as much contribution to the ``Intramolecular Vibration |
| 791 |
> |
Redistribution''[CITE HASE]. Conversely, extra degrees of freedom such |
| 792 |
> |
as the C-H vibrations could yield higher heat exchange rate between |
| 793 |
> |
these two phases and result in a much higher conductivity. |
| 794 |
|
|
| 790 |
– |
|
| 795 |
|
Although the QSC model for Au is known to predict an overly low value |
| 796 |
|
for bulk metal gold conductivity\cite{kuang:164101}, our computational |
| 797 |
|
results for $G$ and $G^\prime$ do not seem to be affected by this |
| 798 |
< |
drawback of the model for metal. Instead, the modeling of interfacial |
| 799 |
< |
thermal transport behavior relies mainly on an accurate description of |
| 800 |
< |
the interactions between components occupying the interfaces. |
| 798 |
> |
drawback of the model for metal. Instead, our results suggest that the |
| 799 |
> |
modeling of interfacial thermal transport behavior relies mainly on |
| 800 |
> |
the accuracy of the interaction descriptions between components |
| 801 |
> |
occupying the interfaces. |
| 802 |
|
|
| 803 |
|
\subsection{Mechanism of Interfacial Thermal Conductance Enhancement |
| 804 |
|
by Capping Agent} |
| 814 |
|
the velocity auto-correlation functions, which is used to construct a |
| 815 |
|
power spectrum via a Fourier transform. |
| 816 |
|
|
| 817 |
+ |
[MAY RELATE TO HASE'S] |
| 818 |
|
The gold surfaces covered by |
| 819 |
|
butanethiol molecules, compared to bare gold surfaces, exhibit an |
| 820 |
|
additional peak observed at a frequency of $\sim$170cm$^{-1}$, which |
| 827 |
|
combination of these two effects produces the drastic interfacial |
| 828 |
|
thermal conductance enhancement in the all-atom model. |
| 829 |
|
|
| 830 |
< |
[MAY NEED TO CONVERT TO JPEG] |
| 830 |
> |
[REDO. MAY NEED TO CONVERT TO JPEG] |
| 831 |
|
\begin{figure} |
| 832 |
|
\includegraphics[width=\linewidth]{vibration} |
| 833 |
|
\caption{Vibrational spectra obtained for gold in different |
