Vibrational excitations of CH4 by electron impact: a close-coupling treatment

We present a quantum dynamical treatment of the vibrational excitation of gaseous methane molecules from single collisions with low-energy electrons. The exact vibrational coupled equations are solved using the four different normal modes of the molecular target and the numerical bound states of each mode. The interaction forces are treated exactly for the static effects while exchange, correlation and polarization contributions are added via parameter-free model potentials. The equations are solved in a body-fixed reference frame using a single-centre expansion formulation and the ensuing inelastic, partial cross sections are compared with experiments and with earlier calculations.