Structures and electron affinities of silicon hydrides Si4Hn (n=2-10)

The silicon hydrides clusters structures and electron affinities of the Si4Hn/Si4Hn− (n=2-10) species have been examined using three density functional theory (DFT) methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. The geometries are fully optimized with each DFT method independently. Three different types of energy separations presented in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable EAad, obtained at the B3LYP and BPW91 levels of theory, are 1.53 or 1.54 eV (Si4H2), 2.45 or 2.47 eV (Si4H3 for Cs←C1) and 2.50 eV for C1←C1 of Si4H3, 1.73 or 1.79 eV (Si4H4), 2.43 or 2.38 eV (Si4H5), 1.61 or 1.55 eV (Si4H6), 2.20 or 2.23 eV (Si4H7), and 2.34 or 2.37 eV (Si4H9). For Si4H8 and Si4H10, there are no reliable EAad but there are reliable VDE. The values of VDE are from 1.29 eV (BPW91) to 1.63 eV (B3LYP) for Si4H8, and from 0.55 eV (B3LYP) to 0.69  eV (BPW91) for Si4H10.