1 Introduction

In this article we present the results of calculations of generalized oscillator strengths and integrated cross sections for the electron impact excitation of Si I from the ground state 3p²(³P₀) to various s,p,d excited states. Si I is an astrophysically important atom. It is seen in absorption spectra from the interstellar medium and stellar photospheres ([Anders & Grevesse 1989]). In order to interpret such data it is important to have accurate electron excitation cross sections and other atomic data for the observed transitions. Very little experimental information is available on atomic cross sections, consequently theory must be relied on to provide the majority of required data.

In the present theoretical approach the 14-electron system of the Si I atom is represented by an independent-particle-model, in which each electron moves independently in an effective potential having the form

$$V({r}) = - \left( 2/r \right) \{~13~[~ H~ ({\rm e}^{r/d}~ -~1)~+~1 ]^{-1}~+~1 \}$$ (1)

where r is the electron-nucleus distance in the units of the Bohr radius a₀, and d, H are adjustable parameters. This potential is inserted into the radial Schrödinger equation which is solved numerically to obtain the wave functions and energy eigenvalues. The parameters d, H are determined by fitting the eigenvalues to the experimental single-particle energy levels. The values d=0.6703, H=1.4952 were obtained from the best fit.