For the saddle-point approximation for Kramers' model for unfolding
(\citet{evans97} Eqn.~3, \citet{hanggi90} Eqn. 4.56c, \citet{vanKampen07} Eqn. XIII.2.2).
\begin{equation}
- \kappa = \frac{D}{l_b l_{ts}} \cdot \exp\p({\frac{-E_b(F)}{k_B T}}) \;,
+ k_u = \frac{D}{l_b l_{ts}} \cdot \exp\p({\frac{-U_b(F)}{k_B T}}) \;,
+ \label{eq:kramers-saddle}
\end{equation}
-where $E_b(F)$ is the barrier height under an external force $F$,
+where $U_b(F)$ is the barrier height under an external force $F$,
$D$ is the diffusion constant of the protein conformation along the reaction coordinate,
$l_b$ is the characteristic length of the bound state $l_b \equiv 1/\rho_b$,
$\rho_b$ is the density of states in the bound state, and
\begin{equation}
l_{ts} = TODO
\end{equation}
+%
+\nomenclature{$U_b(F)$}{The barrier energy as a function of force
+ (\cref{eq:kramers-saddle}).}
+\nomenclature{$l_b$}{The charicteristic length of the bound state $l_b
+ \equiv 1/\rho_b$ (\cref{eq:kramers-saddle}).}
+\nomenclature{$\rho_b$}{The density of states in the bound state
+ (\cref{eq:kramers-saddle}).}
+\nomenclature{$l_{ts}$}{The charicteristic length of the transition
+ state (\cref{eq:kramers-saddle}).}
\citet{evans97} solved this unfolding rate for both inverse power law potentials and cusp potentials.