Relativistic ab initio study on PtF and HePtF

Abstract

The electronic structures and spectroscopic constants of the first three low-lying electronic states (X = 1/2, 3/2, and 5/2) of the linear HePtF complex were investigated by highly accurate relativistic ab initio methods, in which the spin-orbit coupling was taken into account, and compared with the results of PtF. It shows that the complex is significantly different from the typical van der Waals systems because of short He-Pt bond distances (1.80~1.87 A ˚), large He-Pt stretching frequencies (500~600 cm -1 ), considerable binding energies (1400~2500 cm -1 with corrections), and a small electron transfer from helium (about 0.06). However, the topological analysis of the electron density distribution indicates that there is strong van der Waals interaction in the He-Pt bond instead of weak covalent one.

Microwave spectroscopy of platinum monofluoride and platinum monochloride in the X 2Π3/2 states

“…In the case that included spin-orbit coupling, they predicted that the electronic ground state was = 3/2, i.e., 2 3/2 , and there existed the low-lying = 1/2 ( 2 + ) and = 5/2 ( 2 5/2 ) states below 2000 cm −1 for both PtF and PtCl. Similar results were published for PtF by Zou et al, 23 where they predicted that the two lowest = 3/2 and = 1/2 states were nearly degenerate within 200 cm −1 depending on the calculation levels.…”

“…If c 2 Pt5dπ is adjusted to fit the experimental value, we can obtain the value of c 2 Pt5dπ (c 2 Pt5dπ = 0.47), which indicates that the 5d orbital of Pt does not play a dominant role in the unpaired orbital. This contradicts to the theoretical result 22,23 and is highly unlikely. To reduce the value of h 3/2 (Pt), we approximate the ground state of PtF as an admixture of A and B2 states,…”

“…Although the present bond lengths are obtained from an effective rotational constants contaminated with higher order effects omitted in the present analysis, they are in good agreement with the = 3/2 values of the theoretical calculations. 22,23 The obtained PtF distance is found to be about 1.874 Å, which is about 0.14 Å longer than those of PtO. 38 The present PtCl length, of about 2.153 Å, is also longer than that of PtS (Ref.…”

“…Theoretical calculations 22,23 suggested that PtF has three low-lying electronic states, 2 , 2 3/2 , and 2 5/2 , one of which should be the electronic ground state. The -type energysplittings for the > 0 states should be roughly proportional to (J − + 1)(J − + 2) · · · (J + ) J 2 , because the -type doubling energy connecting e and f levels can be expressed using the ladder operator between = ±2 .…”

“…For PtF, the energy separation is predicted to be −205 to 177 cm −1 (Ref. 23) or 855 cm −1 (Ref. 22) above the 2 3/2 ground state and should consist of 70% of 2 + and 30% of 2 1/2 .…”