This simulator visualizes the two intersecting parabolic free energy surfaces at the heart of Marcus theory, letting you see directly how shifting the product parabola relative to the reactant parabola changes the height of the activation barrier at their crossing point, and how the resulting electron transfer rate traces out the full Marcus curve, normal region, peak, and inverted region, as driving force is swept from small to large values relative to a chosen reorganization energy.
Adjust the driving force slider to shift the product energy parabola up or down relative to the fixed reactant parabola, and watch the crossing point, and the activation energy needed to reach it, change in real time. Adjust the reorganization energy slider to widen or narrow the parabolas and see how it shifts the position of the rate-maximizing peak. Watch the rate-versus-driving-force curve build up as you sweep across the normal region, top out at the peak, and fall away into the inverted region, matching the plot to the real 1984 Miller-Closs style experimental data if the comparison overlay is enabled.
Sliders for driving force (delta G) and reorganization energy (lambda) reshape the two intersecting parabolic energy surfaces and update the activation energy and rate in real time; a toggle switches between viewing the energy surface diagram and the full rate-versus-driving-force Marcus curve; an optional overlay displays reference experimental data points alongside the theoretical curve.
Rudolph Marcus reportedly worked out the core mathematics of his electron transfer theory using relatively simple classical mechanics and electrostatics, yet it took experimentalists nearly three decades, until 1984, to build molecules clean enough to actually observe the inverted region his equations predicted, making it one of the longest gaps between theoretical prediction and direct experimental confirmation in modern chemistry.
This simulator visualizes the two intersecting parabolic free energy surfaces at the heart of Marcus theory, letting you see directly how shifting the product parabola relative to the reactant parabola changes the height of the activation barrier at their crossing point, and how the resulting electron transfer rate traces out the full Marcus curve, normal region, peak, and inverted region, as driving force is swept from small to large values relative to a chosen reorganization energy.
This simulator visualizes the two intersecting parabolic free energy surfaces at the heart of Marcus theory, letting you see directly how shifting the product parabola relative to the reactant parabola changes the height of the activation barrier at their crossing point, and how the resulting electron transfer rate traces out the full Marcus curve, normal region, peak, and inverted region, as driving force is swept from small to large values relative to a chosen reorganization energy.
Adjust the driving force slider to shift the product energy parabola up or down relative to the fixed reactant parabola, and watch the crossing point, and the activation energy needed to reach it, change in real time. Adjust the reorganization energy slider to widen or narrow the parabolas and see how it shifts the position of the rate-maximizing peak. Watch the rate-versus-driving-force curve build up as you sweep across the normal region, top out at the peak, and fall away into the inverted region, matching the plot to the real 1984 Miller-Closs style experimental data if the comparison overlay is enabled.
Rudolph Marcus reportedly worked out the core mathematics of his electron transfer theory using relatively simple classical mechanics and electrostatics, yet it took experimentalists nearly three decades, until 1984, to build molecules clean enough to actually observe the inverted region his equations predicted, making it one of the longest gaps between theoretical prediction and direct experimental confirmation in modern chemistry.