Deuteron Quadrupole Coupling in Diatomic ``Hydrides''

Abstract

For LiD and DF, the deuteron quadrupole coupling constant (eqQ/h) has been calculated with single‐determinant SCF‐LCAO‐MO functions. The results obtained are 38 kc/sec for LiD and 373 kc/sec for DF, in rather satisfactory agreement with the recently measured values (30±3 kc/sec for LiD and 340±40 kc/sec for DF). To evaluate the molecular integrals required for the determination of q, a formulation in terms of confocal elliptic coordinates was used. This made possible the introduction of certain auxiliary functions that are very convenient for the calculation of field gradient and related integrals. A comparison of the quadrupole coupling constants obtained with a number of different molecular orbital functions is presented. The results demonstrate the importance of using atomic basis functions with exponents optimized for the molecular system and suggest that exact Hartree‐Fock functions may yield relatively reliable values for field gradients and other one‐electron weak‐interaction parameters. A calculation of the field gradient at the Li nucleus (q = —0.0401 a.u.) yields a value of —3.7×10^—26 cm² for the Li⁷ quadrupole moment when combined with the coupling constant measurement of +346±1 kc/sec.