A test of RRKM theory against numerical simulation for classical chain molecules. II. Decomposition and vibrational relaxation in uniform chains

Schranz, Harold W.; Nordholm, Sture; Freasier, B.C.

doi:10.1016/0301-0104(86)87008-2

Cited by 16 publications

(4 citation statements)

References 46 publications

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“…0022-3654/95/2099-2477$09.00/0 chain molecule decomposition have been carried out to test the applicability of RRKM analysis to the decay of such molecules. [22][23][24] The results showed that uniform Morse bonded chains conformed well with RRKM analysis at energies just above the threshold to decay but less well as the internal energy increased. However, anharmonic effects had to be included in the density of states which determines the rate coefficient for decay, and the nonstatistical effects increased rapidly if the chains were made nonuniform by varying the masses and/or bond strengths.…”

Section: Introductionmentioning

confidence: 73%

“…The Morse parameters Dc = 45.889 kcal mol-1, ft = 1.94 A-1, and rc = 2.28 A are, to provide a chemical reference, chosen to be the bromine molecule intramolecular interaction parameters that have been used in previous investigations. [22][23][24][25][26][27] The mass, m,, is 79.9 amu, which is the atomic mass of bromine. The one-dimensional chain system of pair potentials acting between neighboring atoms is particularly simple to study by statistical mechanics since in the isobaric ensemble, where the known constants are the particle number, N, the pressure, P, and the temperature, T, the bond lengths become independent variables with a bond length probability density e(rft = e-P(<tXr,)+Pr,) e-P(<fi(r,)+Pr,)…”

Section: Model and Methodsmentioning

confidence: 99%

“…Thus, the RRKM analysis incorporates an internal (tight) transition state rather than the loose transition state of the chains in the earlier work. [22][23][24] We also consider the fission of arrays of chains such as that shown in Figure 2. The presence of neighboring chains is expected to increase or introduce nonstatistical effects such as barrier recrossing.…”

Section: Introductionmentioning

confidence: 99%

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Fragmentation of One-Dimensional Monatomic Chains under Tension: Simulation and Statistical Theory

Bolton¹,

Nordholm²,

Schranz³

1995

J. Phys. Chem.

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A one-dimensional monatomic chain under tensile stress has been studied by molecular dynamics. The aim is to determine the lifetime to chain breakage and to ascertain whether this event can be described by simple statistical reaction rate theory. Chains of 2-20 atoms have been simulated. A simple transition state theory, equivalent to a nucleation theory for one-dimensional fluids, gives the main features of the decay rate coefficient as a function of the applied stress. For finite chain lengths an anharmonic RRKM theory provides a more accurate rate coefficient, but chain healing (reversible decay) in the simulated motion causes a significant deviation, particularly at high chain energy. The simulation is extended to chain arrays which show greatly increased nonstatistical effects.

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Section: Introductionmentioning

confidence: 73%

Section: Model and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fragmentation of One-Dimensional Monatomic Chains under Tension: Simulation and Statistical Theory

Bolton¹,

Nordholm²,

Schranz³

1995

J. Phys. Chem.

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“…Much previous work on the dynamical consequences of the application of tensile stress has focussed on the investigation of fragmentation kinetics of linear chains. Studies of energy transfer and equipartition in single chains of coupled anharmonic oscillators have played an essential role in the development of nonlinear dynamics, beginning with the seminal work of Fermi, Pasta and Ulam [32,33] (see, for example, refs [34][35][36][37][38][39][40][41][42][43][44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Bond breaking in a Morse chain under tension: Fragmentation patterns, higher index saddles, and bond healing

Mauguière

Collins

Ezra

et al. 2013

The Journal of Chemical Physics

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We investigate the fragmentation dynamics of an atomic chain under tensile stress. We have classified the location, stability type (indices), and energy of all equilibria for the general n-particle chain, and have highlighted the importance of saddle points with index >1. We show that for an n = 2-particle chain under tensile stress the index 2 saddle plays a central role in organizing the dynamics. We apply normal form theory to analyze phase space structure and dynamics in a neighborhood of the index 2 saddle. We define a phase dividing surface (DS) that enables us to classify trajectories passing through a neighborhood of the saddle point using the values of the integrals associated with the normal form. We also generalize our definition of the dividing surface and define an extended dividing surface (EDS), which is used to sample and classify all trajectories that pass through a phase space neighborhood of the index 2 saddle at total energies less than that of the saddle. Classical trajectory simulations are used to study fragmentation patterns for the n = 2 chain under tension. That is, we investigate the relative probability for breaking one bond versus concerted fission of several (two, in this case) bonds. Initial conditions for trajectories are obtained by sampling the EDS at constant energy. We sample trajectories at fixed energies both above and below the energy of the saddle. The fate of trajectories (single versus multiple bond breakage) is explored as a function of the location of the initial condition on the EDS, and a connection made to the work of Chesnavich on collision-induced dissociation. A significant finding is that we can readily identify trajectories that exhibit bond healing. Such trajectories pass outside the nominal (index 1) transition state for single bond dissociation, but return to the potential well region, possibly several times, before ultimately dissociating.

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Correspondence of canonical and microcanonical rate constants using variational transition state theory for simple bond fissions

Schranz

Raff

Thompson

1990

Chemical Physics Letters

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A test of RRKM theory against numerical simulation for classical chain molecules. II. Decomposition and vibrational relaxation in uniform chains

Cited by 16 publications

References 46 publications

Fragmentation of One-Dimensional Monatomic Chains under Tension: Simulation and Statistical Theory

Fragmentation of One-Dimensional Monatomic Chains under Tension: Simulation and Statistical Theory

Bond breaking in a Morse chain under tension: Fragmentation patterns, higher index saddles, and bond healing

Correspondence of canonical and microcanonical rate constants using variational transition state theory for simple bond fissions

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