Glassing of liquid and viscous flow trigger

A liquid-to-glass transition criterion based on the shutdown of the yield mechanism is proposed. The latter is reduced to the process of delocalization of the atom. When the energy of thermal vibrations of the lattice (grid of bonds) referred to an atom becomes equal to or less than the delocalization energy of the atom, the viscous flow stops and the melt goes into the glassy state. It is assumed that the delocalization of the atom - the limiting displacement of the bridging atom - is a necessary condition for the switching of the valence bond and, consequently, of the most viscous flow of inorganic glasses. The freezing of the delocalization process of the active atom leads to the cessation of fluidity and to the transition of the melt to the glassy state.