Bound States of Positron with Molecules

Abstract

A study for electron binding proves that positrons should be able to form an infinite number of bound states with molecules in the Born-Oppenheimer approximation if the molecular dipole moments are greater than 1.625 Debye (D) (the critical dipole moment), although there is no comprehensive theoretical nor experimental observation. Characteristic features of positron binding with molecules obtained in the Hartree-Fock calculation are discussed in terms of the relationship with the dipole moment of the molecules. It is shown that the current level of the precision of theoretical calculations based on the SCF approach has not verified the theoretical critical dipole moment for the positron binding, and further significant improvement is required. However, the present results, though qualitative, provide much insight of underlying physics of the positron binding and suggest the future direction of research.