Solvent induced vibrational population relaxation in diatomics. II. Simulation for Br2 in Ar

Herman, Michael F.

doi:10.1063/1.452841

Cited by 22 publications

(7 citation statements)

References 56 publications

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“…Nonequilibrium hybrid quantum/ classical surface-hopping approaches have been extensively used to describe VR processes. 99,[101][102][103][104]106,107,110 The general description of the method can be found elsewhere, 85,99 so we concentrate here on the specific features when it is applied to the VR of a quantal normal mode, Q k , of a polyatomic solute molecule like NMAD, dissolved in a liquid like D 2 O. The Hamiltonian of the system can then be written as follows…”

Section: Methodsmentioning

confidence: 99%

“…Nonequilibrium hybrid quantum/classical surface-hopping approaches have been extensively used to describe VR processes. ,− ,,, The general description of the method can be found elsewhere, , so we concentrate here on the specific features when it is applied to the VR of a quantal normal mode, Q k , of a polyatomic solute molecule like NMAD, dissolved in a liquid like D 2 O. The Hamiltonian of the system can then be written as follows H ( Q k , R ) = H normalq ( Q k ) + H cl ( R c l ) + V int ( Q k , R c l ) where H q ( Q k ) is the one-dimensional (1D) quantum harmonic oscillator Hamiltonian of the vibrational normal mode Q k , given by italicĤ normalq ( Q k ) = prefix− normalℏ 2 2 ∂ 2 ∂ Q k 2 + 1 2 normalλ k italicQ̂ k …”

Section: Methodsmentioning

confidence: 99%

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Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D₂O Solution

Bastida

Soler²,

Zúñiga³

et al. 2012

J. Phys. Chem. B

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Hybrid quantum/classical molecular dynamics (MD) is applied to simulate the vibrational relaxation (VR) of the amide I mode of deuterated N-methylacetamide (NMAD) in aqueous (D(2)O) solution. A novel version of the vibrational molecular dynamics with quantum transitions (MDQT) treatment is developed in which the amide I mode is treated quantum mechanically while the remaining degrees of freedom are treated classically. The instantaneous normal modes of the initially excited NMAD molecule (INM(0)) are used as internal coordinates since they provide a proper initial partition of the system in quantum and classical subsystems. The evolution in time of the energy stored in each individual normal mode is subsequently quantified using the hybrid quantum-classical instantaneous normal modes (INM(t)). The identities of both the INM(0)s and the INM(t)s are tracked using the equilibrium normal modes (ENMs) as templates. The results extracted from the hybrid MDQT simulations show that the quantum treatment of the amide I mode accelerates the whole VR process versus pure classical simulations and gives better agreement with experiments. The relaxation of the amide I mode is found to be essentially an intramolecular vibrational redistribution (IVR) process with little contribution from the solvent, in agreement with previous theoretical and experimental studies. Two well-defined relaxation mechanisms are identified. The faster one accounts for ≈40% of the total vibrational energy that flows through the NMAD molecule and involves the participation of the lowest frequency vibrations as short-life intermediate modes. The second and slower mechanism accounts for the remaining ≈60% of the energy released and is associated to the energy flow through specific mid-range and high-frequency modes.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D₂O Solution

Bastida

Soler²,

Zúñiga³

et al. 2012

J. Phys. Chem. B

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“…It has also been shown to be very useful for condensed phase simulations of vibrational transition probabilities, when simplifying approximations can be made. [38][39][40][41][42] In these other surface hopping methods, 20-30 just as with the surface hopping expansion presented in this work, it is the nonadiabatic coupling, which induces the transitions in the adiabatic representation, and it is the generalized coupling, s i f , that plays this role in a general representation. Therefore, the ODR and AODR should have similar advantages, when used with any of these surface hopping methods.…”

Section: Discussionmentioning

confidence: 99%

Optimal representation for semiclassical surface hopping methods

Herman

1999

The Journal of Chemical Physics

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Articles you may be interested inOn the properties of a primitive semiclassical surface hopping propagator for nonadiabatic quantum dynamics A justification for a nonadiabatic surface hopping Herman-Kluk semiclassical initial value representation of the time evolution operator Choosing a good representation of the quantum state wave functions for semiclassical surface hopping calculations A semiclassical surface hopping expansion of the propagator is developed for a general representation of the ''fast'' variable quantum states. The representation can be the adiabatic or diabatic representation or any representation between these two. A particular representation is defined, which is optimal in the sense that it minimizes the integrated interstate coupling. The coupling is integrated over a suitable classical trajectory in this definition. Calculations for a simple one-dimensional curve crossing model problem show that the use of this optimal representation can significantly reduce the importance of multihop terms in the expansion. An approximation to this optimal representation is proposed, which is much simpler to implement numerically. Calculations for the model curve crossing problem demonstrate that this approximate optimal representation provides integrated couplings that are very close to those obtained for the optimal representation. These results suggest that this approximate optimal representation provides a computationally attractive representation for use with semiclassical surface hopping methods, when studying problems with curve crossings.

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“…The minimum of V(q;R) will be a time-dependent quantity, which we will refer to as q min (t). Following Herman, 28 we expand the Morse potentials in our problem out to first order, and then differentiate V(q;R) with respect to q, leading to…”

Section: ͑34͒mentioning

confidence: 99%

Quantum dynamics simulation with approximate eigenstates

Murphrey

Rossky²

1995

The Journal of Chemical Physics

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Articles you may be interested inCommunication: On the consistency of approximate quantum dynamics simulation methods for vibrational spectra in the condensed phase Multidimensional quantum eigenstates from the semiclassical dynamical basis set A semiclassical approximation to quantum dynamics We present a new semiclassical formalism for nonadiabatic dynamics of a quantum subsystem interacting with an explicit bath. The method is based on a stationary phase approach to the bath and a variational principle for the quantum transition amplitudes, for quantum systems represented by approximate wave functions. A new expression for the force exerted on a classical bath by a quantum subsystem is derived which, in the adiabatic limit, reduces to the gradient of the expectation value of the energy. Our new methods for adiabatic and nonadiabatic dynamics are applied to a test problem of vibrational relaxation. For adiabatic dynamics, we find that our new algorithm produces results which converge faster, with increasing basis set size, than calculations performed with the Hellmann-Feynman force; for a limited basis set, our new algorithm gives results that are in better agreement with exact results. For nonadiabatic dynamics, we also find that, in comparison to an earlier algorithm, our new algorithm produces results which converge more rapidly with increasing basis set size. In addition, we find that our new algorithm is more robust with respect to the size of the time step than the earlier algorithm, a result of the implementation of a nuclear coordinate dependent basis.

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Solvent induced vibrational population relaxation in diatomics. II. Simulation for Br2 in Ar

Cited by 22 publications

References 56 publications

Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D₂O Solution

Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D₂O Solution

Optimal representation for semiclassical surface hopping methods

Quantum dynamics simulation with approximate eigenstates

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Solvent induced vibrational population relaxation in diatomics. II. Simulation for Br2 in Ar

Cited by 22 publications

References 56 publications

Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D2O Solution

Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D2O Solution

Optimal representation for semiclassical surface hopping methods

Quantum dynamics simulation with approximate eigenstates

Contact Info

Product

Resources

About

Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D₂O Solution

Hybrid Quantum/Classical Simulations of the Vibrational Relaxation of the Amide I Mode of N-Methylacetamide in D₂O Solution