Ab initio characterization of size dependence of electronic spectra for linear anionic carbon clusters C_n⁻ (n = 4–17)

Abstract

In this article, we determine the ground-state equilibrium geometries of the linear anionic carbon clusters C n- (n = 4-17) by means of the density functional theory B3LYP, CAM-B3LYP, and coupled cluster CCSD(T) calculations, as well as their electronic spectra obtained by the multireference second-order perturbation theory CASPT2 method. These studies indicate that these linear anions possess doublet ²∏(g) or ²∏(u) ground state, and the even-numbered clusters are generally acetylenic, whereas the odd-numbered ones are essentially cumulenic. The energy differences, electron affinities, and incremental binding energies of C n- chains all exhibit a notable tread of parity alternation, with n-even chains being more stable than n-odd ones. In addition, the predicted vertical excitation energies from the ground state to four low-lying excited states are in reasonably good agreement with the available experimental observations, and the calculations for the higher excited electronic transitions can provide accurate information for the experimentalists and spectroscopists. Interestingly, the absorption wavelengths of the 1²∏(u/g) ← X²∏(g/u) transitions of the n-even clusters show a nonlinear trend of exponential growth, whereas those of the n-odd counterparts are found to obey a linear relationship as a function of the chain size, as shown experimentally. Moreover, the absorption wavelengths of the transitions to the higher excited states of C n- series have the similar linear size dependence as well.

Optical Spectroscopy of Small Carbon Clusters from Electron-Impact Fragmentation and Ionization of Fullerene-C60

“…Although a similar calculation of small carbon species has been previously reported (van Orden and Saykally, Malloci et al, Guo et al and references therein), we present our own time-dependent density functional theory (TDDFT) calculations of optically allowed transitions for chain and ring isomers here with an emphasis on the wavelength ranges containing the strongest electronic absorptions. Our results are generally consistent with previous calculations at the same level of theory where available (for the spectral range and sizes of interest here).…”

Ultraslow isomerization in photoexcited gas-phase carbon cluster $${{\rm C}}_{10}^ -$$

“…The rate coefficient for RF radiative relaxation is computed by 43 where A j ( E j ) denotes the Einstein coefficient for transition from electronic state j to the 2 Π u ground state of linear and are computed by considering the electronic states and oscillator strengths as per CASPT2/cc-pVTZ//CCSD(T)/6-31G(d) results reported in ref. 49 . The ratio of the density of states, , in Eq.…”

Fragmentation of Fullerenes to Linear Carbon Chains

“…Although, small carbon clusters have been treated theoretically many times (Van Orden & Saykally (1998); Guo et al (2012) and references therein), we present own TDDFT calculations for chain and ring isomers here with an emphasis on the wavelength ranges containing the strongest electronic absorptions. Our results are generally consistent with previous calculations at the same level of theory where available (for the spectral range and cluster sizes of interest here).…”