Nuclear quadrupole coupling constants of BeH, BeH+ and BeH−: ab initio study of their rovibrational dependence Original Research Article

The 9Be and 2H quadrupole coupling constants of the rovibrational levels of all isotopic variants of BeH(X2Σ+), BeH+(X1Σ+) and BeH− (X1Σ+) are calculated from molecular wavefunctions which explicitly describe nuclear displacement.The strength of the 9Be coupling is predicted to be more than an order of magnitude larger than that of the 2H coupling. The vibrational dependence of the nuclear quadrupole coupling constants is found to be quite significant for all the isotopomers. The qualitative features of the 9Be and 2H quadrupole coupling in these species are consistent with those reported for the corresponding series of lithium hydrides LiH (1Σ+), LiH+ (2Σ+) and LiH− (X2Σ). A comparison with other isoelectric species BH+ (X2Σ+), BH(X1Σ+) and CH+ (X 1Σ+) is also made