[math]E=\frac{\sum_{i=1}^{m}k_{ET}^{(i)}}{\sum_{i=1}^{m}k_{ET}^{(i)}+k_{F}}[/math]
[math]k_{ET}^{(i)}=k_{F}\left ( \frac{R_{0}}{r} \right )^{6}[/math]
