ABINITIO CALCULATION OF NUCLEAR-QUADRUPOLE COUPLING-CONSTANTS OF ROVIBRATIONAL LEVELS OF (BH)-B-11-H-2, (BH)-B-10-H-2, AND (BH)-B-10-H-1 IN THE DOUBLE-MINIMUM B (1)SIGMA(+) ELECTRONIC STATE

The B-11, B-10, and H-2 quadrupole coupling constants of rovibrational levels of (BH)-B-11-H-2, (BH)-B-10-H-2 and (BH)-B-10-H-1 in their B1SIGMA+ state were calculated from molecular wavefunctions which explicitly describe nuclear displacement. The electric field gradient as a function of the internuclear distance was computed by use of the multi-reference configuration interaction approach, the radial rovibrational wavefunctions were obtained by the Fourier grid Hamiltonian method. The double-minimum character of the potential is seen to markedly influence the rovibrational dependences of the boron and deuteron coupling constants. The quadrupole hyperfine structure of all vibrational levels of (BH)-B-11-H-2 and (BH)-B-10-H-2 isotopomer is essentially determined by the relatively strong boron coupling which is perturbed by the deuteron coupling.