APPLICATION OF PAIR CORRELATION THEORY TO POSITRONIUM COMPOUNDS

Extension of weak orthogonality (WO) techniques developed by Szalewicz et al. and coupled pair equations derived by Jeziorski et al. to positronium compounds are presented. These methods enable us to calculate many-electronic positronium compounds with explicitly correlated functions. These methods were applied to positronium hydride (PsH) with Hylleraas-type functions (HTF's), and the total energies, the positron-electron two-photon annihilation rates, and the positronium binding energies were calculated. Extended coupled pair equations were solved by CEPA(2)-type, complete coupled pair (CCP) procedures, and independent pair approximation (IPA) of CCP For the total energies, IPA, CEPA(2), and CCP procedures gave -0.78899, -0.78238, and -0.77471 au, respectively. For the two-photon annihilation rates, the respective procedure gave 2.088, 2.064, and 1.972 ns-1, respectively. © 1995 American Institute of Physics.