3.1.4 Free Energy

   With the expression for the electrostatic energy stored in the circuit (3.5) and the work done by the voltage sources (3.7) the free energy is given by the difference of these two quantities, (2.11).
 $$\begin{align}F=&\frac{1}{2}\begin{bmatrix}\boldsymbol{\varphi_{p,f}}^T&\boldsymb... ...n_i(\varphi_{f_i})q_{f\Sigma}+\sum_{i=1}^{N_c}(\Delta E_{Fi}+E_{Ni}) \end{align}$$
The $\Delta E_{Fi}$ and E_Ni have to be calculated from geometry and material property data. The difference of free energy before and after a tunnel event is then
$$\begin{gather}\Delta F = F_f - F_i. \end{gather}$$