Parity alternation of linear ground-state hydrogenated cationic carbon clusters HCnSi+ (n = 1–10)

Making use of molecular graphics software, we have designed numerous models of HCnSi+ (n = 1–10), and by means of the B3LYP density functional method, performed geometry optimization and calculation on vibrational frequency. The ground-state isomers of HCnSi+ (n = 1–10) are found to be linear with the Si and H atom located at the ends of the Cn chain. When n is even, the Cn chain is polyacetylene-like whereas when n is odd, the Cn chain displays a structure that fades into a cumulenic-like arrangement towards the Si end. According to the results of mass spectrometric investigation available in the literature, the intensities of even-n HCnSi+ are more intense than those of odd-n HCnSi+, implying that the former are more stable than the latter. We detect trends of odd/even alternation in electronic configuration, the highest vibrational frequency, ionization potential, incremental binding energy as well as in certain bond length and certain atomic charge of the linear ground-state structures of the HCnSi+ (n = 1–10) clusters. The calculation results reveal that the even-n cationic clusters are more stable than the odd-n ones.