Electron Affinities of Silicon Hydrides: SiHn (n = 0−4) and Si2Hn (n = 0−6)

The molecular structures and electron affinities of the SiHn/SiHn- (n = 1−4) and Si2Hn/Si2Hn- (n = 0−6) molecules, as well as the silicon atom, have been investigated using density functional theory (DFT) and hybrid Hartree−Fock/density functional theory. Specifically, four different types of electron affinities are reported in this work:  the adiabatic electron affinity (EAad), zero-point corrected EAad (EAzero), the vertical electron affinity (EAvert), and vertical detachment energy (VDE). The basis set used in this work is of double-ζ plus polarization quality with additional s- and p-type diffuse functions, and is denoted as DZP++. Of the six different density functionals used in this work, the BHLYP functional predicted the best molecular structures, and the B3LYP functional predicted the best electron affinities. When compared to the available six experimental electron affinities, the B3LYP functional has an average absolute error of just 0.06 eV. We predict the unknown electron affinities for Si2H2...