The electronic structure
of BeSe and BeTe molecules has been investigated
using the ab initio CASSCF/(MRCI + Q) method at the
spin-free and spin-orbit level. The potential energy curves, the permanent
dipole moment, the spectroscopic constants T
e, R
e, ωe, and B
e, and the dissociation energy D
e are determined in addition to the vertical transition
energy Tv. The molecules’ percentages of ionic character
are deduced, and the trends of the spectroscopic constants of the
two molecules are compared and justified. A ro-vibrational study is
performed using the canonical function approach to calculate the constants E
v, B
v, and D
v and the turning points R
min and R
max. All the ground-state
vibrational levels have also been investigated. The radiative lifetimes
of vibrational transitions among the electronic ground states are
also discussed. The results for BeSe have been compared with the previously
published data while those for BeTe molecules are presented here for
the first time.