Nuclear hyperfine structure in the X3Σ+ state of 91ZrC

Multireference configuration interaction study of the electronic states of ZrC

“…Our estimations are also in good agreement with the experimental result. Rixon et al 18 determined r 0 = 1.8066 Å, which is only 0.002 Å shorter than our MR͑SD͒CI result. The differences are similar comparable to our recent work on NbC and are due mainly to RECPs and basis set incompleteness.…”

“…The ground state of ZrC was not confirmed until very recently by Rixon et al 18 who have determined that the splitting between the 3 ⌺ + and 1 ⌺ + states is 187 cm −1 . Our MR͑S-D͒CI calculations support the idea of a 3 ⌺ + ground state, but the splitting is larger about 1397 cm −1 .…”

“…This is due to the near degeneracy between the 5s orbital of zirconium and the 2p orbital of carbon. 18 In Fig. 1 we have shown the potential energy curves of the singlet states of ZrC and in Table I we have listed the spectroscopic constants of the ground and excited states of ZrC.…”

“…Our determination is in semiquantitative agreement with experiment. Rixon et al 18 have determined that there are three low-lying 1 ⌺ + states at T e 's; 183.83, 1846, and 2463 cm −1 . Therefore the chances of a double minimum are very high for the 1 ⌺ + states of ZrC.…”

“…In spite of significant efforts of theoretical [2][3][4][5][6][7][8][9][10][11] and experimental [12][13][14][15][16][17][18][19] chemists, some transition metal carbides, for example, ZrC, are very far from being well characterized. It was not until recently that Rixon et al 18 have reported for the first time that the ground state of ZrC is 3 ⌺ + with three close low-lying 1 ⌺ + states. However, definitive characterization of higher states was very difficult because of the near degeneracy of the 1 ⌸, 3 ⌸, and 1 ⌺ + states and also because some states are not sufficiently populated in the jet cooled beam for the excitation spectra to be observable.…”