C. W. McCurdy

Discrete basis set approach to nonspherical scattering

A method of calculating scattering amplitudes for nonspherical potentials is proposed. The Lippmann-Schwinger equation for the scattering amplitude is solved in a discrete basis of gaussian functions. Application of the method is made to a model two-center potential. The method is also directly applicable to low energy electron-diatomic molecule scattering.

Photoabsorption cross sections of two‐electron atoms by the coordinate rotation method: Application to H− and several states of He

The coordinate rotation method, recently extended by us to treat photoabsorption processes, is used to obtain photoabsorption cross sections for several two‐electron atoms. The calculations are performed using standard configuration–interaction methods; the need for atomic continuum wavefunctions is completely avoided in this approach. We have computed the photodetachment cross section of H− and photoionization cross sections for He in its ground and 2 1S states. In all cases, the computed cross sections agree well with results obtained by numerical integration and with available experimental data.

A relationship between the many-body theory of inelastic scattering and the distorted wave approximation?

It is shown that the first-order results of the recent many-body theory of inelastic scattering (see abstr. A25430 of 1971) can be derived by a direct application of the distorted-wave and random phase approximations to the usual expression for the inelastic scattering amplitude. The result is derived both in the second quantized formalism and by the standard application of the distorted-wave approximation coupled with the random phase approximation (RPA). The RPA (or time-dependent Hartree-Fock theory) provides the transition density between the initial and inelastically excited states. Possible generalizations of the procedures are discussed.

A simple method for evaluating low-energy electron-molecule scattering cross sections using discrete basis functions?

We present a simple, approximate method for calculating low-energy electron-molecule scattering cross sections using only the results of a basis set diagonalization of the molecular Hamiltonian. The method is based on the approximate conservation of orbital angular momentum in collisions between slow electrons and molecules lacking a permanent dipole moment (low l spoiling). Results are presented for e--H2, and e--N2, in the static-exchange approximation.

Ab initio cross sections for the excitation of the b3σu+ state of H2 by electron impact in the distorted-wave approximation

The authors present differential cross sections for the x 1Σg → b 3Σu transition in H2 at 15 eV incident electron energy. The cross sections are computed in the distorted-wave approximations, using the random-phase approximation for the electronic transition density and a discrete basis set technique for obtaining the distorted waves. The cross sections are found to be in good agreement with experimental data.