The nuclear quadrupole moment of 91Zr from molecular data for ZrO and ZrS

Quasirelativistic Douglas-Kroll calculations at levels up to CCSD(T), combined with the recent experimental zirconium nuclear quadrupole coupling constants for diatomic ZrO and ZrS, yield a Q(Zr-91) of - 176(3) millibarn (mb; 1 barn is 10(-28) m(2)). This value is supported by fully relativistic CCSD(T) calculations using a slightly smaller basis. The new Q(Zr) is much smaller than the available 'atomic' values of -206 to -257 mb. (C) 2000 Elsevier Science B.V. All rights reserved.