Alexandra P. P. Natalense

Note on the generation of Gaussian bases for pseudopotential calculations

We present a technique to generate Cartesian Gaussian bases for electronic configuration and cross-section calculations on molecules. The technique is specially useful for pseudopotential work, when the bases cannot be tabulated because they depend on the specific choice of the pseudopotential.

Annihilation dynamics of positrons in molecular environments

Abstract We present recent results for positron–molecule scattering obtained with the Schwinger multichannel method. Our calculations include integral, differential and momentum transfer cross sections and the annihilation parameter Z eff for C 2 H 2 and C 2 H 4 molecules. We discuss a mechanism for annihilation of positrons in low-energy positron–molecule scattering. We interpret the annihilation process through virtual electronic excitation of the target combined with electronic cloud relaxation and virtual positronium formation. We study the influence of the first electronic state of the target on the cross section and on the annihilation parameter in e + –C 2 H 2 scattering.

Applications of the Schwinger multichannel method with pseudopotentials to electron scattering from polyatomic molecules I: elastic cross sections

This paper is a data basis which includes tables of integral, differential, and momentum transfer cross sections for elastic electron scattering from CF4, CCl4, SiCl4, SiBr4, SiI4, CH3F CH2F2, CHF3, CH3Cl, CH2Cl2, CHCl3, CF3Cl, CF2Cl2, CFCl3, CH3Br, CH3I, SiH3Cl, SiH3Br, SiH3I, GeH3Cl, GeH3Br, SnH3Br, C2H6, Si2H6, Ge2H6, B2H6, Ga2H6, H2O, H2S, H2Se, H2Te, trimethylarsine (TMAs), N2O, and O3. These tables show our new results, along with some of our previously published cross sections, and can easily be compared to future experimental data and other new theoretical results. Our scattering amplitudes were calculated using the Schwinger multichannel method with norm-conserving pseudopotentials. Our results are in good agreement with other theoretical data and experimental results when available.

Applications of the Schwinger Multichannel method with pseudopotentials to electron scattering from polyatomic molecules II: rotational excitation cross sections

This paper reports results for rotational excitation of H2O and H2S molecules by electron impact. It is also a databasis including tables of previously published rotationally resolved cross sections for CH4, SiH4, GeH4, SnH4, PbH4, NH3, PH3, AsH3, SbH3, CF4, CCl4, SiCl4 SiBr4, and SiI4. Our scattering amplitudes were calculated using the Schwinger multichannel method with norm-conserving pseudopotentials and the rotational resolved cross sections were obtained with the help of the adiabatic nuclei rotation approximation. Our results are in good agreement with other theoretical data and experimental results when available.