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Author Yarkony, D. R.
Sponsorship USDOE
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CHEMISTRY ♦ NITROGEN COMPOUNDS ♦ RADIATIONLESS DECAY ♦ ORGANIC OXYGEN COMPOUNDS ♦ ELECTRONIC STRUCTURE ♦ CONFIGURATION INTERACTION ♦ WAVE FUNCTIONS ♦ ALGORITHMS
Abstract The authors consider spin-forbidden radiationless decay of a bound electronic state which is metastable owing to a crossing with a dissociative potential energy surface of different spin-multiplicity. The minimum energy point on the spin allowed surface of intersection of the bound and dissociative potential energy surfaces (the minimum energy crossing point) represents a key bottleneck along the minimum energy dissociation path, and frequently represents the transition state for this process. Thus, the characterization of the minimum energy crossing point yields valuable mechanistic insights into this class of reactions, providing information concerning the feasibility of radiationless decay and the likely decomposition products. Traditional approaches for determining this point using multireference CI wave functions are computationally costly. However, a recently introduced algorithm, which uses analytic energy gradients and determines this point directly, that is without prior characterization of the surface of intersection, has reduced considerably the requisite computational effort. This algorithm is used to consider postulated spin-forbidden radiationless decay channels in tetrahedral N{sub 4}, N{sub 4}({sup 1}A{sub 1}){r_arrow}N{sub 4}({sup 3}A{double_prime}){r_arrow}N{sub 2}(X{sup 1}{Sigma}{sub g}{sup +}) + N{sub 2}(A{sup 3}{Sigma}{sub u}{sup -}) and in the methoxy cation, CH{sub 3}O{sup +}({sup 3}A{sub 2}){r_arrow}CH{sub 3}O{sup +}({sup 1}A{prime}){r_arrow}HCO{sup +}(X{sup 1}{Sigma}{sup +}) + H{sub 2}(X{sup 1}{Sigma}{sub g}{sup +}). For the methoxy cation it is shown, using CI expansions as large as 2.5 million configurations state functions, that {Delta}E = 15.4 kcal/mol, where {Delta}E is defined as the difference between the energy at minimum energy crossing structure and the energy at the minimum on the bound state potential energy surface. 57 refs., 2 figs., 2 tabs.
ISSN 00027863
Educational Use Research
Learning Resource Type Article
Publisher Date 1992-06-17
Publisher Place United States
Journal Journal of the American Chemical Society
Volume Number 114
Issue Number 13


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