Compact boundary-condition-determined wave function for positronium hydride „PsH..

A simple, compact, and accurate wave function for positronium hydride is written as a product of Pade’ approximants for electron–nucleus interactions and of Jastrow functions for electron–electron interactions. Most of the parameters are fixed taking into account both the correct cusp conditions when two particles collide and the correct asymptotic behavior when one or two particles go to infinity. The remaining parameters were optimized by variational Monte Carlo calculations. The energy of this single term wave function is 20.786073(6) hartree and favorably compares with very long configuration interaction expansions and even with explicitly correlated function expansions. The exam of the wave function and of various two-dimensional distribution functions shows that the PsH structure is similar to the hydrogen anion structure, with the positron slightly perturbing it and its motion strongly correlated to the electrons that are squeezed towards each other and towards the nucleus. © 2003 American Institute of Physics. @DOI: 10.1063/1.1605931#