Studies of the photoionization cross sections of acetylene

We have studied the photoionization cross sections and photoelectron asymmetry parameters for all molecular orbitals of acetylene. These cross sections were obtained using accurate frozen-core Hartree–Fock continuum orbitals in the final-state wave function. The Hartree–Fock continuum equations were solved using the iterative Schwinger variational method. These fixed-nuclei cross sections are compared with available experimental data and with results obtained using the Stieltjes moment theory approach and the continuum multiple scattering method. The possible role of a shape resonance in the 1πu→kπg channel and the resonant structure of the σu continuum are discussed in some detail.