Molecular dynamics decoherence

O. Prezhdo B. Schwartz, E. Bittner, and P. Rossky (1996) Quantum decoherence and the isotope effect in condensed phase nonadiabatic molecular dynamics simulations. J. Chem. Phys. 104, p. 5942... 

Modeling Decoherence from Semi-Oassical Molecular Dynamics Simulations... 

The concerted discussion of the topics outlined above should help us advance the new paradigm that addresses our abilities to diagnose and manipulate the entangled states of complex quantum objects and their robustness against decoherence. These abilities are required for quantum information (QI) applications or matter-wave interferometry in molecular, semiconducting or superconducting systems. On the fundamental level, this book may help establish the notion of dynamical information exchange between quantum systems and chart in detail the route from unitarity to classicality. 

In a similar way, chemically induced dimmer configuration prepared on the silicon Si(l 0 0) surface is essentially untitled and differs, both electronically and structurally, from the dynamically tilting dimers normally found on this surface [71]. The dimer units that compose the bare Si(l 0 0) surface tilt back and forth in a low-frequency ( 5 THz) seesaw mode. In contrast, dimers that have reacted with H2 have their Si—Si dimer bonds elongated and locked in the horizontal plane of the surface. They are more reactive than normal dimers. For molecular hydrogen (H2) adsorption, the enhancement is even 10 at room temperature. In a similar way, boundaries between crystaUites and amorphous regions seem to be active sites of chain adsorption on CB surface. CB nanoparticles can be understood as open quantum systems, and the uncompensated forces can be analyzed in terms of quantum decoherence effects [70]. The dynamic approach to reinforcement proposed in this chapter becomes an additional support in epistemology of it, and with data from sub-nanolevel. 

Then the recent notion of nonadiabaticity in electron d3mamics is introduced. To be consistent with the wavepacket bifurcation, we introduce the method of electron wavepacket d3mamics that undergoes bifurcation while being carried along the so-called non-Born-Oppenheimer paths, which also branch due to nonadiabatic interactions. We will further proceed to the discussion about the interaction of molecular nonadiabatic states with intense laser fields. In this way, we penetrate on one hand into unknown domains of molecular properties such as (1) electron-nuclear quantmn entanglement due to nonadiabatic transitions and its experimental observation, (2) coherence and decoherence of electron and nuclear wavepackets, which qualitatively dominate the quantmn mechanical probabiUties of quantum transition dynamics, (3) characteristic phenomena arising from the time-dependent fluctuation of molecular electronic states, (4) the physics of interference between the nonadiabatic djmamics and external fields, and so on. 

Spin relaxation phenomena are usually described by the semiclassical theory developed by Wangsness, Bloch and Redfield and known as the WBR theory or Redfield theory. The semiclassical nature of the theory implies that the spin system is treated quantum mechanically, while the remaining degrees of freedom (such as molecular rotations) are treated classically. Few years ago, Segnorile and Zamar studied the issue of quantum decoherence (loss of system phase memory) in proton NMR of nematic liquid crystals. The spin dynamics - and the decay of the free induction decay - was found to be governed by several different processes, partly of purely quantum nature. During the period under the present review, the same group reported a related work concerned with the Jeener-Broekaert experiment on liquid crystals. ... 

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