Coherent electronic charge

Fig. 15. Pictorial presentation of the physical concept of electron charge transfer in [TCNQ-TTF] as a function of temperature. TR-A each TCNQ resonates between the two harmonic oscillator states at a temperature dependent frequency, co. Electrons on TTF are in an unpaired state (shaded)., TR-B Covalon conduction sets in under the condition, (O v (represented by arrows within TCNQ. TR-C this suggests the diminishing ratio of coherent (straight lines) to incoherent (wavy) parallel lines) with the temperature increase.

As discussed in Section X, irradiation effects are the main enemy in the case of electron microdiffraction. Granier et al. [31,190] found that not only does the irradiation rapidly destroy the sample, but long before, satellite reflections vanish (Fig. 23). In fact, the coherence between charge density waves is much more sensitive than the material itself. 

Electron charges located at a metal-dielectric interface can be caused to undergo coherent fluctuations known as surface plasma oscillations or surface plasmons (SP). The frequency w of such longitudinal oscillations is related to the wave vector k,n by the dispersion relationship. 

Static defects scatter elastically the charge carriers. Electrons do not loose memory of the phase contained in their wave function and thus propagate through the sample in a coherent way. By contrast, electron-phonon or electron-electron collisions are inelastic and generally destroy the phase coherence. The resulting inelastic mean free path, Li , which is the distance that an electron travels between two inelastic collisions, is generally equal to the phase coherence length, the distance that an electron travels before its initial phase is destroyed ... 

Electron Nuclear Dynamics (48) departs from a variational form where the state vector is both explicitly and implicitly time-dependent. A coherent state formulation for electron and nuclear motion is given and the relevant parameters are determined as functions of time from the Euler equations that define the stationary point of the functional. Yngve and his group have currently implemented the method for a determinantal electronic wave function and products of wave packets for the nuclei in the limit of zero width, a "classical" limit. Results are coming forth protons on methane (49), diatoms in laser fields (50), protons on water (51), and charge transfer (52) between oxygen and protons. 

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