2026/03/20 by Rosario R. Riso, Jan Haakon M. Trabski, F Rossi +4 · 1 citation
Engineering · Physics and Astronomy · #Advanced Chemical Physics Studies #Atomic and Molecular Physics #Binding energy #Electron #Molecule #Monte Carlo method #Muon and positron interactions and applications #Polyatomic ion #Positron #Quantum Monte Carlo #physics.chem-ph
paper · pdf · open access · doi:10.1063/5.0334768
published in The Journal of Chemical Physics 165(3) (American Institute of Physics)
openalex publication_date 2026/07/17 · openalex created_date 2026/07/18 · openalex updated_date 2026/08/05
We present the positron coupled cluster singles and doubles (POS-CCSD) method to calculate positron binding energies in molecules. This framework treats electrons and positrons on an equal footing and includes up to simultaneous double-electron-single-positron excitations. We benchmark the approach by computing binding energies for atomic anions and several polar and non-polar polyatomic systems, comparing the results with independent theoretical studies and, where available, experimental data. The fully converged results for H- are in excellent agreement with quantum Monte Carlo and multi-reference configuration interaction results. Quantitative agreement with experiments is not reached in the present study due to the slow convergence of the binding energy with respect to the size of the orbital bases for the electrons and the positron. However, the POS-CCSD results underscore the critical role of electron correlation in the description of electron-positron systems required for a balanced description of these complex systems. In addition, we examine nuclear relaxation effects following positron attachment in LiH.