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Measured and calculated differential cross sections for elastic ͑rotationally unresolved͒ electron scattering from two primary alcohols, methanol ͑CH 3 OH͒ and ethanol ͑C 2 H 5 OH͒, are reported. The measurements are obtained using the relative flow method with helium as the standard gas and a thin aperture as the collimating target gas source. The relative flow method is applied without the restriction imposed by the relative flow pressure conditions on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°-130°. There are no previous reports of experimental electron scattering differential cross sections for CH 3 OH and C 2 H 5 OH in the literature. The calculated differential cross sections are obtained using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Comparison between theory and experiment shows that theory is able to describe low-energy electron scattering from these polyatomic targets quite well.

The authors report results from computational studies of the interaction of low-energy electrons with the purine bases of DNA, adenine and guanine, as well as with the associated nucleosides, deoxyadenosine and deoxyguanosine, and the nucleotide deoxyadenosine monophosphate. Their calculations focus on the characterization of the * shape resonances associated with the bases and also provide general information on the scattering of slow electrons by these targets. Results are obtained for adenine and guanine both with and without inclusion of polarization effects, and the resonance energy shifts observed due to polarization are used to predict * resonance energies in associated nucleosides and nucleotides, for which static-exchange calculations were carried out. They observe slight shifts between the resonance energies in the isolated bases and those in the nucleosides.

We report cross sections for elastic scattering of low-energy electrons by fullerene, C 60 , calculated within the static-exchange approximation. The calculations are carried out via the Schwinger multichannel ͑SMC͒ method, equivalent in this case to the standard Schwinger variational principle. Combining the high parallel efficiency of the SMC method with a quadrature specially adapted to the high symmetry of C 60 facilitates the most demanding step of the calculation and so permits the use of a large basis set. We analyze the structure of the cross section with reference to a simple spherical-shell model, and we compare our results to prior measurements and calculations.

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We present results of measurements and calculations of elastic electron scattering from pyrimidine in the energy range 3-50 eV. Absolute differential and integral elastic cross sections have been measured using a crossed electron-molecule beam spectrometer and the relative flow technique. The measured cross sections are compared with results of calculations using the well-known Schwinger variational technique and an independent-atom model. Agreement between the measured differential cross sections and the results of the Schwinger calculations is good at lower energies but less satisfactory at higher energies where inelastic channels that should be open are kept closed in the calculations.

Studies of the cross sections for electron-impact excitation of the valence states of carbon monoxide, i.e. , the a H, A 'll, a' X+, e'X, d'6, I'X, and D '6 states, have been carried out using the Schwinger multichannel variational method. Both differential and integral cross sections are obtained and compared with available experimental data. Reasonable agreement between the present results and experiment is seen for most of the states, and some differences are discussed. Estimates of the total cross section for electronic excitation of CO by low-energy electrons are provided.PACS number(s): 34.80.6s

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.