Anti-adiabatic state

Anti-adiabatic State - Ground Electronic State of Superconductors... 

Moreover, shift of the ACP substantially increases the density of states (DOS) at FL, HaiEp) = d /dk)p, and induces corresponding decrease of effective electron velocity d /dk)Ep of fluctuating band in this region of k-space. Physically, it represents the system transition from adiabatic (0Ep, or even to a strongly anti-adiabatic state with (O Ep. This effect has crucial theoretical impact. Not only is the ME approximation not valid (impossible to calculate non-adiabatic vertex corrections which represent off-diagonal corrections to the adiabatic ground state), but the adiabatic BOA itself does not hold. 

This has the consequence that the energy barrier for ion transfer through the interface on an adiabatic path in the electronic ground state is extremely high. The situation is only altered if the electronic system reaches an excited state in which the chemical bond is weakened. We must be aware now, that the presence of holes and electrons in a semiconductor already means the presence of excited electronic states A hole in the bond-system of a solid means that an electron has been excited from a binding quantum state to a state with higher energy in the conduction band. This latter state has in most cases anti-... 

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