Positron-atom scattering using pseudo-state energy shifts

Abstract

A method to generate low-energy phase shifts for elastic scattering using bound-state calculations is applied to the problem of e+ - Mg and e+ - Zn scattering after an initial validation on the e+ - Cu system. The energy shift between a small reference calculation and the largest possible configuration interaction calculation of the lowest energy pseudo-state is used to tune a semi-empirical optical potential. The potential was further fine-tuned by utilizing the energy of the second lowest pseudo-state. The s- and p-wave phase shifts for positron scattering from Mg and Zn are given from threshold to the first excitation threshold. The e+ - Mg cross section has a prominent p-wave shape resonance at an energy of about 0.096 eV with a width of 0.106 eV. The peak cross section for e+ - Mg scattering is about 4800 a_0^2 while Z_eff achieves a value of 1310 at an energy of 0.109 eV.

15 pages, 15 figures, submitted to PRA (updated following referee comments)

References in corpus (9)

• Quantum Monte Carlo calculations of neutron-alpha scattering
• Quantum Monte Carlo treatment of elastic exciton-exciton scattering
• Calculation of the positron bound state with the copper atom
• Large dimension Configuration Interaction calculations of positron binding to the group II atoms
• o-Positronium scattering off H and He
• Convergence of the partial wave expansion of the He ground state
• Convergence of CI single center calculations of positron-atom interactions
• Generating phase shifts from pseudo state energy shifts
• The existence of a 2Po excited state for the e+Ca system

Cited by in corpus (10)

• Positron-molecule interactions: resonant attachment, annihilation, and bound states
• Positron scattering and annihilation on noble gas atoms
• Recent progress in the description of positron scattering from atoms using the Convergent Close-Coupling Theory
• Atoms which can bind positrons
• Detection of positron-atom bound states through resonant annihilation
• Positron scattering and annihilation from the hydrogen molecule at zero energy
• Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules, using a Gaussian basis
• Relativistic coupled-cluster single-double calculations of positron-atom bound states
• Positron attachment to the He doubly excited states
• Effect of atomic electric quadrupole moment on positron binding