Theoretical study on spectroscopy and molecular constants of the ground and low-lying excited states of GeO molecule

The potential energy curves (PECs) of X-1 Sigma (+),a(,3)Sigma(+), a(3)Pi,A(1)Pi states for GeO molecule are calculated by the multireference configuration interaction method (MRCI) and MRCI with the Davidson's corrections (MRCI+Q) with aug-cc-pVTZ basis set. All these states involved dissociate into the same dissociation channel Ge(P-3)+O(P-3). For the four states, the spectroscopic parameters (R-e, D-e, omega(e), B-e, omega(e)chi(e) and T-e) have been obtained, which shows that our results are in very good agreement with the experimental value and other theoretical data at MRCI+Q level. The dipole moments of these states are also obtained. In addition, based on the accurate results of spectroscopic constants at MRCI+Q level, the first 30 vibrational states are determined for the four low-lying electronic states when J=0. The vibrational levels G(v) and inertial rotation constants B-v at MRCI+Q level are calculated when J=0, the results of X-1 Sigma(+) and A(1)Pi states are in concordance with the available other theoretical values and experimental work. The dissociation limits, dissociation energies, electronic configurations at equilibrium internuclear distance for a(,3)Sigma(+), a(3)Pi states also are predicted for the first time.