The electronic structures of all trans form of permethyl-oligosilane radical cation with longer chain: A density functional theory study

Hybrid density functional theory (DFT) calculations have been carried out for neutral, radical cation and dication of permethyl-oligosilane, Sin(CH3)2n+2 (n = 4–30), to elucidate the electronic structures at ground and low-lying excited states. It was found that a hole is distributed in both the Si–Si skeleton (main chain) and methyl group (side chain) in the case of shorter chain-lengths below n = 6, whereas the spin density (hole) in the methyl group becomes significantly smaller in longer chain-lengths (n > 7). The IR-band of radical cation were assigned on the basis of theoretical calculations.