Density Functional Theory Study of Cyano- and Dicyanopolyacetylene Cations

Abstract

Density functional theory calculations are presented for the linear cyano-and dicyanopolyacetylene cations C 4 N 2 + , C 6 N 2 + , HC 3 N + , and HC 5 N + . The structures, vibrational frequencies, and dipole moments are computed by unrestricted BLYP theory with the 6-311G* and 6-311G** basis sets. Calculated vibrational frequencies of the ground electronic states of the cations are in excellent agreement with experimental observations by Bondybey and co-workers and Maier and co-workers.

Structure, Spectroscopic Properties and Reactions of Interstellar Molecule HC2N and Isomers :Ab initio Study

“…It would be important to recall that our previous experience [23][24][25][26][27] with the BLYP/6-311G** theory as applied to similar carbon clusters suggests that the harmonic frequencies computed here would agree with experimental values mostly to within 30 cm −1 without invoking the empirical scaling factors.…”

“…We employ the MP2 and the CCSD(T) methods with the 6-311G** basis set for the structures and energies of the isomers. The density functional theory (BLYP/6-311G**), which we found very economical and also accurate for calculating the harmonic frequencies of the carbon clusters in a number of works, [23][24][25][26][27] is used to compute the infrared frequencies and to find out the reaction paths by intrinsic reaction coordinate (IRC) analysis. We predict several isomers of the molecule.…”

Rotationally resolved A2Πu←X 2Πg electronic transition of NC6N+

“…The value for B 0 Љϭ0.018 753 3(55) cm Ϫ1 is close to the B e -value of 0.018 67 cm Ϫ1 as obtained from density functional calculations. 18 A simulation using these constants proves that the stronger feature in Fig. 1 at 15 247.23͑3͒ cm Ϫ1 corresponds to the R-branch band head of the A 2 ⌸ 3/2 ←X 2 ⌸ 3/2 system.…”

Vibronic structure of the2Πuground electronic state of dicyanoacetylene cation revisited by PFI-ZEKE photoelectron spectroscopy andab initiocalculations

“…Small hydrocarbon chains have been proposed as good candidates for DIBS [24] and several studies have been carried out to study the vibronic structure of C 4 N + 2 by fluorescence [25][26][27], IR and visible absorption spectroscopy [28,29], as well as by photoelectron spectroscopy (PES) [27,[30][31][32] and mass spectrometry [33]. Up to now, only few calculations are available about the electronic and vibrational structure of the C 4 N + 2 cation [34][35][36][37][38][39]. The ground electronic state of this cation is a 2 u state.…”

“…[68], k from Ref. [34], l measurements in liquid phase, m measurements in Ne matrix, n ω values fitted with the perturbative approach of Ranković et al [38].…”