Applications of the Schwinger multichannel method to electron-molecule collisions

Abstract

We discuss some recent developments in the implementation of the Schwinger multichannel method for electron-molecule collision calculations. The evaluation of matrix elements involving the operator VGp+'V, previously accomplished by insertion of a Gaussian basis on either side of Gz+', is now done by direct numerical quadrature. This approach avoids the necessity of very large Gaussian basis sets, allowing the size of the basis to reAect only the dynamical requirements of the scattering wave function. We 6nd that the reduction in the required basis size results in improved efBciency, in spite of the additional numerical efFort of performing the quadrature. Trial applications to electron-CH4 scattering in the static-exchange approximation and to electronic excitation of H2 illustrate the excellent convergence characteristics of the procedure.

Elastic scattering of low-energy electrons by benzene

“…17,18 We do not repeat that description here but rather focus on the details of the present calculations. Both our SE and SEP calculations used the fixed-nuclei approximation at the experimental D 6h geometry, r͑C-C͒ϭ1.397 Å and r͑C-H͒ ϭ1.084 Å.…”

“…Benzene is an intrinsically interesting target molecule due to its geometry and symmetry and is of additional interest in light of recent experimental and theoretical studies. [1][2][3][10][11][12] Our calculations employed the Schwinger multichannel ͑SMC͒ method 17,18 as implemented for parallel computers 19 and were carried out both in the static-exchange and in the static-exchange-plus-polarization ͑SEP͒ approximations. This study may be considered a first step toward studies of more complex aromatic molecules such as the fluoro-, chloro-, and fluorochlorobenzenes 20 or the DNA bases.…”

Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

“…Our calculations were carried out with the Schwinger multichannel method (SMC) 26,27 with pseudopotentials. 28 The method was recently reviewed 29 and here we will provide only the relevant points for the present calculations.…”

Electron collisons with cyclobutane

“…The Schwinger multichanel (SMC) method [9][10][11] and its implementation with pseudopotentials [12] have been described in detail in several publications. We will only discuss the points relevant for the present calculations.…”