Calculations of positron binding and annihilation in polyatomic molecules

Abstract

A model-potential approach to calculating positron-molecule binding energies and annihilation rates is developed. Unlike existing ab initio calculations, which have mostly been applied to strongly polar molecules, the present methodology can be applied to both strongly polar and weakly polar or nonpolar systems. The electrostatic potential of the molecule is calculated at the Hartree-Fock level, and a model potential that describes short-range correlations and long-range polarization of the electron cloud by the positron is then added. The Schrodinger equation for a positron moving in this effective potential is solved to obtain the binding energy. The model potential contains a single adjustable parameter for each type of atom present in the molecule. The wave function of the positron bound state may be used to compute the rate of electron-positron annihilation from the bound state. As a first application, we investigate positron binding and annihilation for the hydrogen cyanide (HCN) molecule. Results for the binding energy are found to be in accord with existing calculations, and we predict the rate of annihilation from the bound state to be $\Gamma =0.1$--$0.2\times 10^9{\text{s}}^{-1}$.

arXiv comment13 pages, 6 figures, accepted by J. Chem. Phys

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Cited by in corpus (9)

• Many-body theory of positron binding in polyatomic molecules
• Positron Binding and Annihilation in Alkane Molecules
• Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules, using a Gaussian basis
• Effect of chlorination on positron binding to hydrocarbons: experiment and theory
• Effect of molecular constitution and conformation on positron binding and annihilation in alkanes
• Many-Body Theory Calculations of Positron Scattering and Annihilation in H${}_2$, N${}_2$ and CH${}_4$
• Many-body Theory Calculations of Positron Binding to Halogenated Hydrocarbons
• Many-body theory calculations of positronic-bonded molecular dianions
• Coupled cluster theory for positron binding in anions and polyatomic molecules