title: Ab initio quantum Monte Carlo study of the positronic hydrogen cyanide molecule.
abstract: Quantum Monte Carlo methods are used to investigate the binding of a positron to the hydrogen cyanide (HCN) and lithium hydride (LiH) molecules. Our value of the adiabatic positron affinity (PA) of LiH of 1.010(3) eV is very close to the best theoretical value of 1.005 eV, obtained from variational calculations using explicitly correlated Gaussian basis sets [K. Strasburger, J. Chem. Phys. 114, 00615 (2001)]. We have obtained a reliable estimate of 0.0378(48) eV for the PA of the HCN molecule, which is almost 20 times larger than that obtained at the Hartree-Fock level, and strongly supports the binding of a positron in the electrostatic field of the HCN molecule. Our results show the importance of correlation effects for describing weakly bound positronic molecular complexes.
authors.affiliation: Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan. happysea@mac.com
authors.forename: Yukiumi
authors.initials: Y
authors.lastname: Kita
authors.forename: Ryo
authors.initials: R
authors.lastname: Maezono
authors.forename: Masanori
authors.initials: M
authors.lastname: Tachikawa
authors.forename: Mike
authors.initials: M
authors.lastname: Towler
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Needs