The structure of e+LiH

Abstract

The stochastic variational method (SVM) has been used toconfirm the prediction of a quantum Monte Carlo (QMC) calculation(Bressanini et al 1998 J. Chem. Phys. 109 1716)that a positron can be bound to the lithium hydride molecule(LiH). The adiabatic approximation was not made andthe nuclear motion was explicitly included in the calculation.A completely ab initio calculation gave a positron bindingenergy of 0.613 eV and constitutes an explicit demonstration ofbinding not restricted to the Born-Oppenheimer approximation.The fixed-core variant of the SVM was also used with aLi+ 1s2 core. The positron binding energy in thefixed-core SVM was 0.909 eV, which is approximately the sameas that previously reported in the QMC calculation. The meaninter-nuclear radius was 3.96 a0 and the 2γ annihilationrate of the e+LiH ground state was 1.64×109 s-1.