Nonadiabatic dynamics condensed phase

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... 

In order to discuss various aspects of a mixed quantum-classical treatment of photoinduced nonadiabatic dynamics, we consider five different kinds of molecular models, each representing a specihc challenge for a mixed quantum-classical modeling. Here, we introduce the specifics of these models and discuss the characteristics of their nonadiabatic dynamics. The molecular parameters of the few-mode models (Model I-IV) describing intramolecular nonadiabatic dynamics are collected in Tables I-V. The parameters of Model V describing various aspects of nonadiabatic dynamics in the condensed phase will be given in the text. 

In the MQC mean-field trajectory scheme introduced above, all nuclear DoF are treated classically while a quantum mechanical description is retained only for the electronic DoF. This separation is used in most implementations of the mean-field trajectory method for electronically nonadiabatic dynamics. Another possibility to separate classical and quantum DoF is to include (in addition to the electronic DoF) some of the nuclear degrees of freedom (e.g., high frequency modes) into the quantum part of the calculation. This way, typically, an improved approximation of the overall dynamics can be obtained—albeit at a higher numerical cost. This idea is the basis of the recently proposed self-consistent hybrid method [201, 202], where the separation between classical and quantum DoF is systematically varied to improve the result for the overall quantum dynamics. For systems in the condensed phase with many nuclear DoF and a relatively smooth distribution of the electronic-vibrational coupling strength (e.g.. Model V), the separation between classical and quanmm can, in fact, be optimized to obtain numerically converged results for the overall quantum dynamics [202, 203]. 

G. Hanna and R. Kapral. Nonadiabatic dynamics of condensed phase rate processes. Acc. Chem. Res., 39(l) 21-27, Jan 2006. 

Persico Granucci focus on the nonadiabatic dynamics of excited states in condensed phase. Static environmental effects are discussed in terms of the change of the PES with respect to the isolated molecule, while dynamic effects are described in terms of transfer of energy and momentum between the chromophore (or reactive centre) and the surrounding molecules. 

In the present chapter, we will focus on the simulation of the dynamics of photoexcited nucleobases, in particular on the investigation of radiationless decay dynamics and the determination of associated characteristic time constants. We use a nonadiabatic extension of ab initio molecular dynamics (AIMD) [15, 18, 21, 22] which is formulated entirely within the framework of density functional theory. This approach couples the restricted open-shell Kohn-Sham (ROKS) [26-28] first singlet excited state, Su to the Kohn-Sham ground state, S0, by means of the surface hopping method [15, 18, 94-97], The current implementation employs a plane-wave basis set in combination with periodic boundary conditions and is therefore ideally suited to condensed phase applications. Hence, in addition to gas phase reference simulations, we will also present nonadiabatic AIMD (na-AIMD) simulations of nucleobases and base pairs in aqueous solution. 

We have presented nonadiabatic ab initio molecular dynamics simulations of the photophysical properties of a variety of nucleobases and base pairs. In addition to the canonical tautomers a number of rare tautomers have been investigated. Moreover, effects of substitution and solvation have been studied in detail. The simulations of nonradiative decay in aqueous solution, in particular, demonstrate the strength of the na-AIMD technique employed here as it permits the treatment of solute and solvent on an equal footing. Condensed phase calculations can be directly compared with those in the gas phase because the same computational setup can be used. 

R J. Rossky (1998) Nonadiabatic quantum dynamics simulation using classical baths. In G. Ciccotti B. Berne, and D. Coker, editors, Classical and quantum dynamics in condensed phase simulations. World Scientific, Dordrecht, p. 515... 

In their studies of nonadiabatic dynamics in condensed phase, Rossky and his colleagues emphasized the role of stochastic perturbations that actually decohere the surroimded quantum states (solute state) [327, 468]. This is one of the most significant phenomena in the dynamics of open systems. 

In the following sections we show how the quantum-classical Liouville equation and quantum-classical expressions for reaction rates can be deduced from the full quantum expressions. The formalism is then applied to the investigation of nonadiabatic proton transfer reactions in condensed phase polar solvents. A quantum-classical Liouville-based method for calculating linear and nonlinear vibrational spectra is then described, which involves nonequilibrium dynamics on multiple adiabatic potential energy surfaces. This method is then used to investigate the linear and third-order vibrational spectroscopy of a proton stretching mode in a solvated hydrogen-bonded complex. 

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