ROVIBRATIONAL DEPENDENCE OF THE AB-INITIO NUCLEAR-QUADRUPOLE COUPLING-CONSTANTS IN THE X(3)SIGMA- STATE OF NH

The N-14 and H-2 quadrupole coupling constants of rovibrational levels of (NH)-N-14-H-1 and (NH)-N-14-H-2 in their ground electronic states have been calculated from molecular wavefunctions which explicitly des cribe nuclear motion. For the lowest vibrational states the N-14 quadr upole coupling is predicted to be relatively strong and to decrease ra pidly with vibrational excitation. The deuteron coupling in (NH)-N-14- H-2 is found to be weak and its behaviour is similar to that of other first-row hydrides. The change with rotational excitation is unimporta nt. For about six lowest vibrational levels, the quadrupole hyperfine patterns of (NH)-N-14-H-2 in its X3SIGMA- state are dominated by relat ively strong nitrogen coupling.