Vibrational Dynamics of the Neutral Naphthalene Molecule from a Tight-Binding Approach

Van-Oanh, Nguyen-Thi; Parneix, and Pascal; Bréchignac, Philippe

doi:10.1021/jp026250e

Cited by 45 publications

(60 citation statements)

References 27 publications

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“…We use for H i intra the tight-binding model developed by Van Oanh et al (2002). This simple quantum model was parameterized to reproduce energetic and vibrational properties of isolated PAH molecules.…”

Section: Atomic Modelmentioning

confidence: 99%

Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

Rapacioli¹,

Calvo

Joblin³

et al. 2006

A&A

141

145

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Aims. The competition between the formation and destruction of coronene clusters under interstellar conditions is investigated theoretically. Methods. The unimolecular nucleation of neutral clusters is simulated with an atomic model combining an explicit classical force field and a quantum tight-binding approach. Evaporation rates are calculated in the framework of the phase space theory and are inserted in an infrared emission model and compared with the growth rate constants. Results. It is found that, in interstellar conditions, most collisions lead to cluster growth. The time evolution of small clusters (containing up to 312 carbon atoms) was specifically investigated under the physical conditions of the northern photodissociation region of NGC 7023. These clusters are found to be thermally photoevaporated much faster than they are reformed, thus providing an interpretation for the lowest limit of the interstellar cluster size distribution inferred from observations. The effects of ionizing the clusters and density heterogeneities are also considered. Based on our results, the possibility that PAH clusters could be formed in PDRs is critically discussed.

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Section: Atomic Modelmentioning

confidence: 99%

Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

Rapacioli¹,

Calvo

Joblin³

et al. 2006

A&A

141

145

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“…The residual discrepancy is the overall redshift of approximately 100 cm −1 with respect to experiment, a result from the initial parametrization of the present tight-binding model to reproduce experimental data. 35 Clearly, modeling closer to the ab initio level should alleviate this specific issue.…”

Section: B Results and Discussionmentioning

confidence: 99%

“…In the applications presented below, the intramolecular dynamics of naphthalene has been modeled using a tightbinding potential 35 already used several times in the past. [36][37][38][39][40][41] Ab initio calculations considered the equilibrium geometry of naphthalene predicted by this model, varying the location of the argon atom along the three symmetry axes of the molecules, or within its symmetry planes as depicted in Fig.…”

Section: Potential and Parametersmentioning

confidence: 99%

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A simple but accurate potential for the naphthalene-argon complex: Applications to collisional energy transfer and matrix isolated IR spectroscopy

Calvo

Falvo

Parneix

2013

The Journal of Chemical Physics

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An explicit polarizable potential for the naphthalene-argon complex has been derived assuming only atomic contributions, aiming at large scale simulations of naphthalene under argon environment. The potential was parametrized from dedicated quantum chemical calculations at the CCSD(T) level, and satisfactorily reproduces available structural and energetic properties. Combining this potential with a tight-binding model for naphthalene, collisional energy transfer is studied by means of dedicated molecular dynamics simulations, nuclear quantum effects being accounted for in the path-integral framework. Except at low target temperature, nuclear quantum effects do not alter the average energies transferred by the collision or the collision duration. However, the distribution of energy transferred is much broader in the quantum case due to the significant zero-point energy and the higher density of states. Using an ab initio potential for the Ar-Ar interaction, the IR absorption spectrum of naphthalene solvated by argon clusters or an entire Ar matrix is computed via classical and centroid molecular dynamics. The classical spectra exhibit variations with growing argon environment that are absent from quantum spectra. This is interpreted by the greater fluxional character experienced by the argon atoms due to vibrational delocalization.

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“…Formation rates were calculated from collision rates between molecules and clusters, which depend on the temperature and density of the cloud, and the probability of sticking at each collision. This last value is calculated from MD simulations using the TB-MM approach combining the TB model of Van Oanh et al (2002) with a classical intermolecular pair potentials as mentioned above. To describe the evaporation which might follow a UV photon absorption, one needs to compare the rate of energy relaxation either by IR emission or by evaporation of one molecule.…”

Section: Stability In Ngc 7023nmentioning

confidence: 99%

PAH-related Very Small Grains in photodissociation regions: implications from molecular simulations

Rapacioli

Spiegelman

Joalland

et al. 2011

EAS Publications Series

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Abstract. The analysis of mid-IR emission suggests that a population of PAH-related very small grains containing a few hundreds of atoms are present in the deep regions of molecular clouds, although no specific species has been identified yet. In this review, we discuss several candidates for these grains: neutral and ionised PAH clusters and complexes of PAHs with Si atoms. The theoretical modelling of the properties of such molecular complexes or nanograins is a challenging task. We first present an overview of quantum chemistry derived models which can be efficiently used on-the-fly in extensive sampling of the potential energy surfaces, as required by structural optimization, classical molecular dynamics or Monte Carlo algorithms. From the simulations, various observables can be determined, such as the binding energies, finite temperature IR spectra, nucleation and evaporation rates. We discuss the relevance of those candidates in the molecular clouds photodissociation regions and propose constrains and perspectives for the nature and size of those very small grains.

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Vibrational Dynamics of the Neutral Naphthalene Molecule from a Tight-Binding Approach

Cited by 45 publications

References 27 publications

Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

A simple but accurate potential for the naphthalene-argon complex: Applications to collisional energy transfer and matrix isolated IR spectroscopy

PAH-related Very Small Grains in photodissociation regions: implications from molecular simulations

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