On the influence of vibrational modes and intramolecular isomerization processes on the NMR parameters of bullvalene: A Feynman path integral – ab initio investigation

Böhm, Michael; Ramı́rez, Rafael; Schulte, Joachim

doi:10.1016/j.chemphys.2007.09.008

Cited by 18 publications

(3 citation statements)

References 45 publications

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“…Still, it may be the only satisfactory approach when, for instance, the effects of conformational motion are considered. However, although the importance of molecular motion has been clearly recognized and studied for nuclear shielding constants (see the recent study of bullvalene [240]), for spin-spin coupling constants, there are very few such studies.…”

Section: Modeling Of the Effects Of Molecular Motionmentioning

confidence: 98%

The quantum-chemical calculation of NMR indirect spin–spin coupling constants

Helgaker

Jaszuński

Pecul

2008

Progress in Nuclear Magnetic Resonance Spectroscopy

265

256

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Section: Modeling Of the Effects Of Molecular Motionmentioning

confidence: 98%

The quantum-chemical calculation of NMR indirect spin–spin coupling constants

Helgaker

Jaszuński

Pecul

2008

Progress in Nuclear Magnetic Resonance Spectroscopy

265

256

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“…We have analyzed UV-vis and photoelectron spectra, as well as hyperfine splitting constants and NMR chemical shifts. [26][27][28] The experimental inverse isotope effect in the lattice parameter of ice Ih has been explained recently by a combination of DFT calculations of phonon properties and PI simulations. 29 The isotope effect in the melting point of ice Ih and the negative thermal expansion of ice Ih at low temperatures has been reproduced realistically by quantum PI simulations.…”

Section: Introductionmentioning

confidence: 99%

Ice and water droplets on graphite: A comparison of quantum and classical simulations

Ramı́rez

Singh

Müller‐Plathe

et al. 2014

The Journal of Chemical Physics

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Ice and water droplets on graphite have been studied by quantum path integral and classical molecular dynamics simulations. The point-charge q-TIP4P/F potential was used to model the interaction between flexible water molecules, while the water-graphite interaction was described by a Lennard-Jones potential previously used to reproduce the macroscopic contact angle of water droplets on graphite. Several energetic and structural properties of water droplets with sizes between 10(2) and 10(3) molecules were analyzed in a temperature interval of 50-350 K. The vibrational density of states of crystalline and amorphous ice drops was correlated to the one of ice Ih to assess the influence of the droplet interface and molecular disorder on the vibrational properties. The average distance of covalent OH bonds is found 0.01 Å larger in the quantum limit than in the classical one. The OO distances are elongated by 0.03 Å in the quantum simulations at 50 K. Bond distance fluctuations are large as a consequence of the zero-point vibrations. The analysis of the H-bond network shows that the liquid droplet is more structured in the classical limit than in the quantum case. The average kinetic and potential energy of the ice and water droplets on graphite has been compared with the values of ice Ih and liquid water as a function of temperature. The droplet kinetic energy shows a temperature dependence similar to the one of liquid water, without apparent discontinuity at temperatures where the droplet is solid. However, the droplet potential energy becomes significantly larger than the one of ice or water at the same temperature. In the quantum limit, the ice droplet is more expanded than in a classical description. Liquid droplets display identical density profiles and liquid-vapor interfaces in the quantum and classical limits. The value of the contact angle is not influenced by quantum effects. Contact angles of droplets decrease as the size of the water droplet increases which implies a positive sign of the line tension of the droplet.

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“…33 Thus one has to restrict such simulations to reactive processes where (nuclear) quantum effects can be neglected. In recent Feynman pathintegral Monte Carlo studies, it had been shown that (intramolecular) reactions of non-hydrogen atoms can be described adequately in a classical approximation for temperatures $298 K. 34,35 In rearrangement processes of hydrogen atoms, quantum uctuations are non-negligible in the vicinity of (and even below) room-temperature. The heavy coarse-grained beads, see below, in the present reactive approach imply that a classical approximation should be sufficient.…”

Section: Introductionmentioning

confidence: 99%

A coarse-grained molecular dynamics – reactive Monte Carlo approach to simulate hyperbranched polycondensation

Zhang

Wang

et al. 2014

RSC Adv.

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A coarse-grained molecular dynamics (CG-MD) and reactive Monte Carlo (RMC) hybrid method (CG-MD + RMC) has been developed to investigate the hyperbranched polycondensation of 3,5-bis(trimethylsiloxy) benzoyl chloride to poly(3,5-dihydroxybenzoic acid). The CG force field to describe the formation of the hyperbranched macromolecules has been extracted from all-atom molecular dynamics simulations by the mapping technology of iterative Boltzmann inversion. In the mapping process branched poly(3,5-dihydroxybenzoic acid) in an all-atom description has been employed as a target object to derive the CG force field for hyperbranched polymers. In the RMC simulations, the reactivity ratio of the functional groups has been optimized by fitting experimental data with the iterative dichotomy method (Macromolecules, 2003, 36, 97). Using such a simulation framework, detailed information including the molecular weight, the molecular weight distribution and the branching degree of a specific polymerization process has been derived. Radial distribution functions of the atomistic and coarsegrained systems are in excellent agreement. A good agreement between the present simulations and experiment has been demonstrated, too. Especially, the intramolecular cyclization fraction has been reproduced quantitatively. This work illustrates that the present reactive CG-MD + RMC model can be used for quantitative studies of specific hyperbranched polymerizations.

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On the influence of vibrational modes and intramolecular isomerization processes on the NMR parameters of bullvalene: A Feynman path integral – ab initio investigation

Cited by 18 publications

References 45 publications

The quantum-chemical calculation of NMR indirect spin–spin coupling constants

The quantum-chemical calculation of NMR indirect spin–spin coupling constants

Ice and water droplets on graphite: A comparison of quantum and classical simulations

A coarse-grained molecular dynamics – reactive Monte Carlo approach to simulate hyperbranched polycondensation

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