Table 1.

Force field parameters used in MD simulations. The usual factor of ½ in stretching and bending interactions is included in ${\mathit{k}}_{\mathit{a}}$ and ${\mathit{k}}_{\mathit{b}}$.

Force Field Parameters for Polybutadiene Crosslinked with Sulfur
${\mathit{U}}_{\mathbf{L}\mathbf{J}}=4\mathit{ϵ}\left[{\left(\frac{\mathit{\sigma }}{\mathit{r}}\right)}^{\mathbf{12}}-{\left(\frac{\mathit{\sigma }}{\mathit{r}}\right)}^{\mathbf{6}}\right]$	$ϵ \left[\frac{\mathrm{k}\mathrm{c}\mathrm{a}\mathrm{l}}{\mathrm{m}\mathrm{o}\mathrm{l}}\right]$	$\sigma \left[\mathrm{\AA }\right]$
$\left({\mathbf{C}\mathbf{H}}_{\mathbf{3}}-\right)\mathbf{‚}(-\mathbf{S}-)$	0.209	3.723
$\left({-\mathbf{C}\mathbf{H}}_{\mathbf{2}}-\right)\mathbf{‚}(-\mathbf{S}-)$	0.172	3.723
$\left(-\mathbf{C}\mathbf{H}=\right),(-\mathbf{S}-)$	0.170	3.673
$\left(-\mathbf{C}\mathbf{H}<\right),(-\mathbf{S}-)$	0.128	3.525
$\left(-\mathbf{S}-\right),(-\mathbf{S}-\mathbf{S}-)$	0.250	3.550
$\left(-\mathbf{S}-\right),(-\mathbf{S}-)$	0.250	3.550
${\mathit{U}}_{\mathbf{b}\mathbf{o}\mathbf{n}\mathbf{d}}={\mathit{k}}_{\mathbf{b}}{\left(\mathit{r}-{\mathit{r}}_{\mathbf{0}}\right)}^{\mathbf{2}}$	$k_{\mathrm{b}}\left[\frac{\mathrm{k}\mathrm{c}\mathrm{a}\mathrm{l}}{\mathrm{m}\mathrm{o}\mathrm{l} {\mathrm{\AA }}^2}\right]$	$r_0\left[\mathrm{\AA }\right]$
${\mathbf{C}\mathbf{H}}_{\mathbf{3}}-\mathbf{C}\mathbf{H}=$	317.0	1.500
$-{\mathbf{C}\mathbf{H}}_{\mathbf{2}}-\mathbf{C}\left(>\mathbf{C}<\right)$	260.0	1.526
$=\mathbf{C}\mathbf{H}-\mathbf{C}\left(>\mathbf{C}<\right)$	317.0	1.500
$-\mathbf{S}-\mathbf{C}\left(>\mathbf{C}<\right)$	222.0	1.810
${\mathit{U}}_{\mathbf{a}\mathbf{n}\mathbf{g}\mathbf{l}\mathbf{e}}={\mathit{k}}_{\mathbf{a}}{\left(\mathit{\theta }-{\mathit{\theta }}_{\mathbf{0}}\right)}^{\mathbf{2}}$	$k_{\mathrm{a}}\left[\frac{\mathrm{k}\mathrm{c}\mathrm{a}\mathrm{l}}{\mathrm{m}\mathrm{o}\mathrm{l} {\mathrm{r}\mathrm{a}\mathrm{d}}^2}\right]$	${\theta }_0\left[\mathrm{d}\mathrm{e}\mathrm{g}\mathrm{r}\mathrm{e}\mathrm{e}\mathrm{s}\right]$
${\mathbf{C}\mathbf{H}}_{\mathbf{3}}-\mathbf{C}\mathbf{H}=\mathbf{C}\mathbf{H}-$	70.0	118.0
$-\mathbf{S}-\mathbf{S}-\mathbf{C}\left(>\mathbf{C}<\right)$	68.0	103.7
$\mathbf{C}\left(>\mathbf{C}<\right)-\mathbf{S}-\mathbf{C}\left(>\mathbf{C}<\right)$	62.0	98.9
$\mathbf{C}\left(>\mathbf{C}<\right)-\mathbf{S}-\mathbf{C}\mathbf{H}<$	62.0	98.9
$-{\mathbf{C}\mathbf{H}}_{\mathbf{2}}-\mathbf{C}\left(>\mathbf{C}<\right)-\mathbf{S}-$	---	---
$=\mathbf{C}\mathbf{H}-\mathbf{C}\left(>\mathbf{C}<\right)-\mathbf{S}-$	---	---
$=\mathbf{C}\mathbf{H}-\mathbf{C}\left(>\mathbf{C}<\right)-{\mathbf{C}\mathbf{H}}_2-$	---	---
$=\mathbf{C}\mathbf{H}-\mathbf{C}\mathbf{H}\left(-{\mathbf{C}\mathbf{H}}_{\mathbf{2}}\right)-\mathbf{S}-$	---	---