Electronic and vibrational properties of diamondlike hydrocarbons

The electronic and vibrational properties of small diamondoids are systematically investigated using an ab initio molecular orbital method. The obtained formation energies, ionization potentials, and affinity energies as well as the HOMO-LUMO gaps of the concerned diamondoids all exhibit the polymantane-order-dependent feature. We also propose the fragmentation channels with the lowest dissociation energies of cationic and neutral products, based on our calculated dissociation energies of the neutrals and positively charged diamondoids. It is, furthermore, revealed that the products arising from the dissociation of a diamondoid preferably contain some tiny hydrocarbons. In addition, the vibrational frequencies of the diamondoids are predicted, which may serve as a reference in identifying the hydrocarbon systems in the experiment.