A Systematic Application of Density Functional Theory to Some Carbon-Containing Molecules and Their Anions

Abstract

Eight medium-sized carbon-containing molecules: linear carbon chains C n (n = 6−9), triacetylene (C6H), tetracyanoethylene (C6N4), 1,1,1-trifluoroacetone enolate (CF3CHCHO), and C4O have been studied using six different density functional or hybrid Hartree−Fock density functional methods with a double-ζ basis set with polarization and diffuse functions (DZP++). Optimized geometries, harmonic vibrational frequencies, and adiabatic electron affinities were estimated and compared to known experimental values. The harmonic vibrational frequencies showed an overall agreement with experimental fundamentals of approximately 4−6% with one exception, the BHLYP functional. Average absolute errors in electron affinities estimated with the BP86, BLYP, and B3LYP functionals all show agreement of better than 0.2 eV with experiment and provide a viable method of predicting electron affinities for molecules of the same type as studied here.

VIBRATIONALLY EXCITED C 6 H

“…and ν 10 at 210 cm −1 (Brown et al 1999;Cao & Peyerimhoff 2001). From consideration of the rotational constants and line intensities, one tentatively assigns the 2 Σ and 2 Δ components to the lowest ν 11 bending mode of C 6 H. The second 2 Σ component of the Renner-Teller pair of the ν 11 mode was not observed in the laboratory or in IRC+10216 (Cernicharo et al 2008), probably because it lies too high in energy and is not sufficiently populated.…”

“…Approximate energies of the 2 Σ and 2 Δ vibronic components of the ν 11 bending vibrational level of C 6 H. The energy of the ν 11 level is from a quantum calculation in the harmonic approximation (Brown et al 1999;Cao & Peyerimhoff 2001); the A 2 Σ electronic state from a photoelectron spectrum (Taylor et al 1998); and the vibronic components of ν 11 were estimated from relative intensities of rotational lines (see Section 3.4).…”

Reactions of [FORMULA][F][RM]C[/RM][SUP]-[/SUP][INF]n[/INF][/F][/FORMULA] and [FORMULA][F][RM]C[/RM][INF]n[/INF][RM]H[/RM][SUP]-[/SUP][/F][/FORMULA] with Atomic and Molecular Hydrogen

“…An additional consideration is that in the SIFT technique, the reactant ions are studied in their ground electronic and vibrational state due to collisional cooling by the helium bath gas. Based on the nature of the experiment, the similarity of our ion source to others, and the ab initio results of others (Raghavachari 1989;Szczepanski, Ekern, & Vala 1997;Brown, Rienstra-Kiracofe, & Schaefer 1999), the reaction rate constants measured in this study are assigned to the reactions of linear carbon chain anions with H 2 and H. …”

Conformational Barrier for Fullerene−Porphyrin−Fullerene Triad

“…All of the calculations were performed using a suite of Gaussian 03 programs. 43 The accuracy of these methods has been demonstrated by Schaefer and co-workers on electron affinities of aromatic compounds 44,45 and fullerene-based covalently linked dyads and triads; 46 furthermore, this approach has been successfully applied on the C 60 PC 60 system in our previous work. 35 To study the PES of C 60 PC 60 revolving around the axial C-C bond, we take the rotational reaction coordinates as shown in Scheme 1.…”