Is a Molecular Adiabatic Approximation Appropriate to Positronic Atoms and Molecules?

Abstract

The adiabatic approximation to positronic atoms and molecules was considered as an option to the computationally unfeasible methods that treat all particles in a common footing, in two different approaches communicated in the 37th PSPA. Here we present further assessment and comparison of the two approaches as a way of evaluating the potential of adiabatic or, as we found preferable, molecular approaches.

Modified adiabatic method: bound state of thee+HF molecule

“…If the positron is weakly bound and occupies mostly outer regions of the molecule, then its motion is likely to be significantly slower than that of electrons; therefore, we assume it is a light pseudonucleus. It is treated on equal footing with other nuclei in Mohallem's method [20][21][22][23][24][25][26], in which the nuclear kinetic energy operator is included in the electronic Hamiltonian, so that equation ( 1) is a purely electronic problem. In our method, the motions of true (heavy) nuclei are separated first and the wavefunction in equation (1) describes the state of all electrons and positron.…”

“…This study is based on adiabatic separation of positronic motion, which has been proposed independently by Mohallem [20][21][22][23][24][25][26]. Our approach is based on a different idea of Stachowiak and Boroński [27].…”