Theoretical and Experimental Study of Dimerization of Substituted Phenylacetylenes

Sevin, Fatma; Balcioglu, Nurettin

doi:10.1007/978-1-4615-3700-7_31

Cited by 2 publications

(2 citation statements)

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“…The nonadiabatic representation is not unique, and the choice made for MCMM is a valence bond Hamiltonian, in which V 11 ( V 22 ) is the energy of a valence bond state with the reactant's (product's) bonding pattern, and V 12 is the resonance energy. This kind of nondiagonal representation of the Hamiltonian has been used in a variety of contexts for modeling reactive systems. ,− In MCMM, the Born−Oppenheimer potential energy surface is obtained as the lowest eigenvalue of the matrix V , and it reproduces the higher-level data in the vicinity of each electronic structure data point. The MCMM method is therefore a general fitting scheme for creating semiglobal PESs for reactive systems.…”

Section: Introductionmentioning

confidence: 99%

Efficient Molecular Mechanics for Chemical Reactions: Multiconfiguration Molecular Mechanics Using Partial Electronic Structure Hessians

Lin

Albu

et al. 2004

J. Phys. Chem. A

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a The rate constant including tunneling is then given by k CVT/MT = κ MT k CVT , where κ MT is the transmission coefficient (denoted κ CVT/MT in Ref. 1 ), and MT is ZCT, SCT, LCT(0), LCT, or µOMT. The definition for the transmission coefficient is given in Ref. 1 . See Section 2.3 of text for MCMM notation.b With n max = 0, where n max is the highest vibrational quantum number included in LCT calculations; for direct dynamics, it is the number of energetically allowed final states.c With n max = 0; the n max for MCMM is determined according to the protocol described in Section 3.2 of text. Note that in direct dynamics and MCMM, the potential energy surfaces and reaction paths are not identical, and thus the energetically allowed highest excited states are not necessarily the same.d With n max = 0. e With n max = 1.

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Section: Introductionmentioning

confidence: 99%

Efficient Molecular Mechanics for Chemical Reactions: Multiconfiguration Molecular Mechanics Using Partial Electronic Structure Hessians

Lin

Albu

et al. 2004

J. Phys. Chem. A

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“…Note that the nonadiabatic representation is not unique, but the kind we have in mind here is a valence bond Hamiltonian in which V 11 is the energy of a valence bond state with the reactant's bonding pattern, V 22 is the energy of a valence bond state with the product's bonding pattern, and V 12 is their resonance energy. Such representations have been used in a variety of contexts for modeling reactive systems in the past. − The MCMM method is actually a general fitting scheme for creating semiglobal PESs for reactive systems, and because a PES is constructed, it is not, strictly speaking, a direct dynamics method at all; however, it accomplishes the main objective of any direct dynamics scheme for VTST/MT calculations in that it allows one to carry out the entire dynamics calculation from a reasonably small amount of electronic structure data without requiring the traditional human judgment associated with the “art” of fitting multidimensional functions. The whole fitting process is unique and automatic with one exception, namely, the decision where to locate the input data.…”

Section: Introductionmentioning

confidence: 99%

Molecular Mechanics for Chemical Reactions: A Standard Strategy for Using Multiconfiguration Molecular Mechanics for Variational Transition State Theory with Optimized Multidimensional Tunneling

2001

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Multiconfiguration molecular mechanics (MCMM) is an extension of molecular mechanics to chemically reactive systems. This dual-level method combines molecular mechanics potentials for the reactant and product configurations with electronic structure Hessians at the saddle point and a small number of nonstationary points to model the potential energy surface in the reaction swath region between reactants and products where neither molecular mechanics potential is valid. The resulting semiglobal potential energy surface is used as input for dynamics calculations of tunneling probabilities and variational transition state theory rate constants. In this paper, we present a standard strategy for applying MCMM to calculate rate constants for atom transfer reactions. In particular, we propose a general procedure for determining where to calculate the electronic structure Hessians. We tested this strategy for a diverse test suite of six reactions involving hydrogenatom transfer. It yields reasonably accurate rate constants as compared to direct dynamics using an uninterpolated full potential energy surface at the same electronic structure level. Furthermore, the rate constants at each of several successively more demanding levels of dynamical theory are also predicted accurately, which indicates that the MCMM potential energy surface accurately predicts many different details of the potential energy surface with a limited number of electronic structure Hessians.

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Theoretical and Experimental Study of Dimerization of Substituted Phenylacetylenes

Cited by 2 publications

References 0 publications

Efficient Molecular Mechanics for Chemical Reactions: Multiconfiguration Molecular Mechanics Using Partial Electronic Structure Hessians

Efficient Molecular Mechanics for Chemical Reactions: Multiconfiguration Molecular Mechanics Using Partial Electronic Structure Hessians

Molecular Mechanics for Chemical Reactions: A Standard Strategy for Using Multiconfiguration Molecular Mechanics for Variational Transition State Theory with Optimized Multidimensional Tunneling

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