Sphericalhyphen;complexhyphen;opticalhyphen;potential (SCOP) model for electronndash;monosilane (SiH4) collisions at 30ndash;400 eV: Total (elastic+absorption), momentum transfer, and differential cross sections

摘要

We report nonempirical quantum mechanical calculations on the total (elastic+absorption), momentum transfer, and differential cross sections forehyphen;SiH4collisions at intermediate and high energies (30ndash;400 eV). A parameterhyphen;free and energyhyphen;dependent sphericalhyphen;complexhyphen;optical potential (SCOP) is evaluated for theendash;SiH4system. The real part of the SCOP consists of three local terms, namely static, exchange, and polarization. The static interaction is generated very accurately from nearhyphen;Hartreendash;Fock onehyphen;center silane wave functions, while the exchange effects are accounted for in the freehyphen;electronhyphen;gashyphen;exchange (FEGE) model. The polarization potential is evaluatedabinitioin a parameterhyphen;free approximation of Jain and Thompson. The imaginary term of the total SCOP represents loss of flux due to inelastic channels via an energyhyphen;dependent absorption potential calculated from target electron density and shorthyphen;range statichyphen;exchange force in the quasifree model with Pauli blocking lsqb;Staszewskaetal.; J. Phys. B16, L281 (1983)rsqb;. Two versions of this absorption potential are employed; one with an undistorted density and the other with a polarized density determined approximately from first order target wave functions. The later version is more successful when the final results are compared with experiment. The total SCOP is treated exactly in a partialhyphen;wave analysis using the variablehyphen;phase approach to yield complex phase shifts. Our final total cross sections compare very well with the only available measurements of Sueoka and Mori. However, below 50 eV, present total cross sections overestimate the experimental data within 10percnt;. The effect of absorption potential is to reduce the elastic cross sections significantly; this reduction is more dramatic in case of the differential cross sections (DCS); for example, the reduced DCS are exposed to more pronounced structure. Interestingly, theendash;SiH4reduced DCS are very close in shape to the correspondingendash;Ar cross sections above 60 eV.