THE DIPOLE-MOMENT OF AUH

A finite-field peturbation approach is used to study the relativistic and relativistic-correlation contributions to electric properties of AuH. The relativistic terms in the molecular Hamiltonian are approximated by the so-called Cowan-Griffin perturbation operator whose first-order contributions are evaluated in a large basis set of Gaussian functions. The electron correlation contribution is accounted for by using the many body perturbation theory methods. Both the relativistic and electron correlation effects as well as the mixed relativistic-correlation contributions are shown to be important in accurate predictions of the dipole moment of AuH. According to the present study the dipole moment of the 1-SIGMA+ ground electronic state of AuH calculated at the experimental equilibrium bond distance of 2.880 bohr is found to be in the range between 0.6-0.7 a.u. The quadrupole moment of AuH is shown to have positive sign in the relativistic-correlated treatment while its negative value is predicted in nonrelativistic calculations. The parallel component of the dipole polarizability tensor is found to be equal to about 44. a.u. It is also shown that the electric property values of AuH are strongly affected by the electron correlation effects involving the next-to-valence shell of the Au atom. The valence approximation gives quite unrealistic results for both the electron correlation and relativistic contributions to electric properties of AuH.