Electronic Structure of LiH and Quadrupole Moment of Li7

Hartree—Fock self-consistent field calculations of the Roothaan (LCAO—MO) type have been carried out on an electronic computer for LiH using an extended set of basis functions. Configuration interaction calculations result in a total molecular energy of 99.3% and a dissociation energy of 89.3% of the experimental values. It is found that large contributions occur from pπ orbitals in configuration interaction. Using a general method developed in the present work, the electric-field gradient is calculated in LiH. With Klemperer, Gold, and Wharton's measurement of the LiH quadrupole coupling constant, the quadrupole moment of the Li7 nucleus is found to be —4.4×10—26 cm2. This sign is unambiguously determined to be negative, in agreement with theoretical predictions from nuclear models. The dipole moment of LiH is calculated to be —5.89 D, and the quadrupole coupling constant of deuterium in LiD is calculated to be 35.3 kc/sec.