Vibrational relaxation of chloroiodomethane in cold argon

Jain, Amber; Sibert, Edwin L.

doi:10.1063/1.4823837

Cited by 2 publications

(2 citation statements)

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“…Despite this issue, we note that PRISM-MC correctly predicts all known (qualitative and some quantitative) trends in monodisperse systems -a) with increasing grafting density the mid-range attractive well deepens and shifts to higher interparticle distances (Figure 1); b) with increasing matrix chain length the attractive well depth deepens (Supplementary Information); c) the value of the well depth seen at 0.65 chains/d 2 is of the same order of magnitude (~0.3-0.5kT in Supplementary Information) as that seen for similar systems in recent simulation studies [11,12] on systems with graft length of 10 monomers and matrix lengths of 10-70 monomers, and particle sizes approximately 10 times monomer size at high grafting density (~0.76 chains/nm 2 ). The ability of PRISM-MC to predict the same qualitative trends as other theoretical methods [13], and, in certain cases quantitative agreement with prior simulations [11,12] for monodisperse grafts suggests that this approach is capable of predicting correct qualitative trends for the polydisperse polymer grafted nanoparticles as well.…”

Section: Polydispersity For Tuning the Potential Of Mean Force Betweesupporting

confidence: 67%

Polydispersity for Tuning the Potential of Mean Force between Polymer Grafted Nanoparticles in a Polymer Matrix

2013

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We present an integrated theory and simulation study of polydisperse polymer grafted nanoparticles in a polymer matrix to demonstrate the effect of polydispersity in graft length on the potential of mean force between the grafted nanoparticles. In dense polymer solutions, increasing polydispersity in graft length reduces the strength of repulsion at contact and weakens the attractive well at intermediate interparticle distances, completely eliminating the latter at high polydispersity index. The reduction in contact repulsion is attributable to polydispersity relieving monomer crowding near the particle surface, especially at high grafting densities. The elimination of the midrange attractive well is attributable to the longer grafts in the polydisperse graft length distribution that introduce longer range steric repulsion and alter the wetting of the grafted layer by matrix chains. Dispersion of the grafted particles is stabilized by increased penetration or wetting of the polydisperse grafted layer by the matrix chains. This work demonstrates that at high grafting densities, polydispersity in graft length can be used to stabilize dispersions of grafted nanoparticles in a polymer matrix at conditions where monodisperse grafts would cause aggregation.

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Section: Polydispersity For Tuning the Potential Of Mean Force Betweesupporting

confidence: 67%

Polydispersity for Tuning the Potential of Mean Force between Polymer Grafted Nanoparticles in a Polymer Matrix

2013

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“…Initially, an amount of excess energy is introduced to excite the vibration mode of interest and then its energy is monitored as a function of time. The solvent acceptors can be identified through the analysis of time-dependent mode-to-mode energy transfer. , Most reported NEMD studies utilized classical force fields, ,− empirical valence bond (EVB) potentials, − and the hybrid quantum mechanics/molecular mechanics (QM/MM) method. − For solute molecules with a large amount of excess energy, the system can travel deep into the anharmonic region far from the equilibrium region of the potential energy surface (PES), possibly leading to considerable changes in the relevant dipole moments. Moreover, if the solute and solvent are strongly coupled, partial charge transfer between them can also take place.…”

Section: Introductionmentioning

confidence: 99%

Vibrational Energy Relaxation of Deuterium Fluoride in d-Dichloromethane: Insights from Different Potentials

Zhang

Vázquez

Harvey

2021

J. Chem. Theory Comput.

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Vibrationally excited deuterium fluoride (DF) formed by fluorine atom reaction with a solvent was found (Science, 2015, 347, 530) to relax rapidly (less than 10 ps) in acetonitrile-d 3 (CD 3 CN) and dichloromethane-d 2 (CD 2 Cl 2 ). However, insights into how CD 2 Cl 2 facilitates this energy relaxation have so far been lacking, given the weak interaction between DF and a single CD 2 Cl 2 . In this work, we report the results of reactive simulations with a two-state reactive empirical valence bond (EVB) potential to study the energy deposited into nascent DF after transition-state passage and of nonequilibrium molecular dynamics simulations using multiple different potential energy functions to model the relaxation dynamics. For these second simulations, we used the standard Merck molecular force field (MMFF) potential, an MMFF-based covalent-ionic empirical valence bond (EVB) potential (EVB CI ), a newly developed potential [referred to as MMFF(rDF)] which extends upon the MMFF potential by making the DF/CD 2 Cl 2 interaction depend on the value of the DF bond stretching coordinate and by taking the anisotropic charge distribution of the solvent molecules into account, the polarizable atomic multipole optimized energetics for biomolecular applications (AMOEBA) potential, and the quantum mechanics/molecular mechanics (QM/ MM) potential. The relaxation is revealed to be highly sensitive to the potential used. Neither standard MMFF nor EVB CI reproduces the experimentally observed rapid relaxation dynamics, and they also fail to provide a good description of the interaction potential between DF and CD 2 Cl 2 as calculated using CCSD(T)-F12. This is attributed to the use of a point-charge model for the solute and to failing to model the anisotropic electrostatic properties of CD 2 Cl 2 . The MMFF(rDF), AMOEBA, and QM/MM potentials all reproduce the CCSD(T)-F12 two-body DF---CD 2 Cl 2 interaction potential rather well but only with the QM/MM approach is fast vibrational relaxation obtained (lifetimes of ∼288, ∼186, and ∼8 ps, respectively), which we attribute to differences in the solute−solvent local structure. With QM/MM, a unique "many-body" interaction pattern in which DF is in close contact with two solvent Cl atoms and more than three solvent D atoms is found, but this structure is not seen with other potentials. The QM/ MM dynamics also display enhanced solute−solvent interactions with vibrationally excited DF that induce a DF band redshift and hence a resonant overlap with solvent CD modes, which facilitate the intermolecular energy transfer. Our work also suggests that potentials used to model energy relaxation need to capture the fine structure of solute−solvent interactions and not just the twobody part.

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Vibrational relaxation of chloroiodomethane in cold argon

Cited by 2 publications

References 49 publications

Polydispersity for Tuning the Potential of Mean Force between Polymer Grafted Nanoparticles in a Polymer Matrix

Polydispersity for Tuning the Potential of Mean Force between Polymer Grafted Nanoparticles in a Polymer Matrix

Vibrational Energy Relaxation of Deuterium Fluoride in d-Dichloromethane: Insights from Different Potentials

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