Computational investigation by ab initio methods of the spectroscopic characteristics of hafnium monosulfide

The lowest-lying electronic states of (HfS)-Hf-180-S-32 molecule have been described by using the theoretical ab initio methods, state-averaged full valence complete active space self-consistent field (SA-CASSCF) and multireference configuration interaction with single and double excitation (MRCI-SD). These calculations have predicted 22 electronic states below 40,124 cm(-1). The unobserved states (2)(1)Delta, (1)(1)Gamma, (3)(1)Sigma(+), (2)(1)Pi, (1)(1)Phi, (3)(1)Delta, (3)(1)Pi, (4)(1)Sigma(+), (1)(3)Phi, (1)3 Sigma(-) , (2)(3)Pi, (2)(3)Sigma(-), (3)(3)Pi, and (4)(3)Pi have been explored for the first time. The potential energy curves (PECs) have been constructed, and the term energy values at equilibrium T-e, vibrational constants omega(e), and omega(e)chi(e) have been calculated for all predicted states. Also, the permanent dipole moments (PDMs) as well as the transition dipole moments (TDMs) have been examined and presented as function of the internuclear distance R. In addition, by employing the spin-orbit coupling in the calculations, 43 Omega(+/-) components have been obtained below 40,645 cm(-1). The observed states, named A(1)Sigma(+) and B-1 Pi, have been assigned respectively as (1)(3)Pi(0) and (1)(3)Pi(1) of (1)(3)Pi. All the calculated spectroscopic constants are found in good agreement with the experiment.

Automated summary

The lowest-lying electronic states of the (HfS)-Hf-180-S-32 molecule have been described using theoretical ab initio methods, predicting 22 electronic states and exploring previously unobserved states. Potential energy curves have been constructed, spectroscopic constants calculated, and agreement with experimental results observed.