A spin polarization transfer approach to intermolecular interactions between hydrocarbon aromatic compounds and free radicals

Aileen Lozsán, Pedro Nieto, Sócrates Acevedo, Vladimiro Mujica

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Abstract

Using an effective spin-dependent Heisenberg Hamiltonian, we have modeled the interaction between closed-shell aromatic molecules and the free radical methyl. Physically, the model is based on a proportionality relationship, suggested by McConnell (McConnell, H. J. Chem. Phys. 1963, 41, 1910), between the product of the spin densities on each molecular fragment and the interaction energy of the system. The spin polarization, initially on the radical, is partly transferred to the molecule as the two fragments approach each other determining an effective spin interaction. The parameters of the effective Heisenberg-type Hamiltonian are determined through ab initio calculations of the electronic structure of the complex at the UMP2 level. Our calculations confirm the validity of a cage model recently proposed by Mujica et al. (Mujica, V.; Nieto, P.; Puerta, L.; Acevedo, S. Energy Fuels 2000, 14, 632) for spin trapping in fragments of asphaltenes while providing a consistent semiempirical approach to the interaction and stabilization problems.

Original languageEnglish (US)
Pages (from-to)10374-10379
Number of pages6
JournalJournal of Physical Chemistry A
Volume106
Issue number43
DOIs
StatePublished - Oct 31 2002
Externally publishedYes

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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