The mechanism by which the energy is released at the level of the flavoenzyme molecule during the transfer of two electrons.

The model of a mechanism producing the excitation of two electrons by the rotation of an orbital is presented functioning at the level of the flavoenzyme molecule. According to this model, during the transfer of two electrons from an NADH coenzyme to a flavoenzyme molecule, in a reaction cavity of the flavoprotein, two (Fe2+:S) covalent bonds are formed. Subsequently to the electric polarization induced by the formation of some intermolecular connections and by some fixed ions, and (Fe2+:S) orbital turns with an angle, having the nucleus of the sulfur atom as a pivot point, in such a way that an (Fe2+) ions is left out from the covalent bond, and it is replaced by a proton (released from a water molecule). A new (S:H) orbital is formed. Within this (S:H) orbital, the proton moves towards the nucleus of the sulfur atom, from 2.10 A degrees internuclear distance (position in which the proton was included by the orbital rotation) to 1.36 A degrees internuclear distance--corresponding to the length of the (S:H) covalent bond. By the proton movement, the two electrons of the (S:H) orbital arrive on an excitation state level. Then, they fall to their fundamental level and deliver two quanta of electronic excitation, which are transmitted further and help the synthesis of an ATP molecule.