The importance of an accurate target wave function in variational calculations for (e^{+}-H_{2}) scattering

Abstract

Using the complex Kohn method, we have calculated variational values of phase shifts and the annihilation parameter, Z_{eff}, for the elastic scattering of positrons by molecular hydrogen. Our results are sensitive to small changes in the accuracy of the wave function representing the target hydrogen molecule. We have developed a systematic approach to demonstrate that, at low positron energies, there are particular forms of the Kohn trial wave function for which the results of variational calculations are not reliable, even when the target wave function accounts for as much as 96.8% of the correlation energy of H_{2}. We find that reliable results can be recovered if our calculations are extended to admit more sophisticated target wave functions accounting for 99.7% of the correlation energy. Remaining discrepancies between theory and experiment are briefly discussed.

Changed content in sections 3.1 and 4 to take referee's comments into account

Cited by in corpus (7)

• 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
• Many-Body Theory Calculations of Positron Scattering and Annihilation in H${}_2$, N${}_2$ and CH${}_4$
• Effect of positron-atom interactions on the annihilation gamma spectra of molecules
• Anomaly-free singularities in the generalized Kohn variational method
• Equivalence of the generalized and complex Kohn variational methods
• Variational Calculations of Positronium Scattering with Hydrogen