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Ab Initio Study of the Geometries and Vibrational Properties of the Low-Lying Electronic States of Neutral and Anionic M 3 (M = P, As, Sb, and Bi): The Photoelectron Spectroscopy of the Anions

2002; American Chemical Society; Volume: 106; Issue: 20 Linguagem: Inglês

10.1021/jp020325x

1520-5215

Heechol Choi, Chung-Min Park, Kyoung Koo Baeck,

Inorganic Chemistry and Materials

The geometries and vibrational properties of the low-lying electronic states of neutral and anionic of M3 (M = P, As, Sb, and Bi) are studied using the coupled-cluster singles, doubles, and noniterative triples (CCSD(T)) method as well as the density functional theory (B3LYP-DFT) method. For P3-, the and states are almost degenerate. The state, however, turns out to be the lowest state for As3-, Sb3-, and Bi3-, and the adiabatic excitation energies of the state are 0.6, 0.9, and 1.0 eV, respectively. In the anionic trimers of all four elements, another singlet state, 1A1(C2v), is located about 0.3−0.4 eV above ; the energy gap between these states is compared to the splittings between the first two peaks in the photoelectron spectra of these anions. For all of the neutral trimers, the adiabatic and vertical energetic splittings between the Jahn−Teller components of the X2E' ' and 4E' states are calculated to be only 0.04−0.08 eV. Another quartet state, is 0.4 eV higher, almost equal, 0.2 eV lower, and 0.3 eV lower in energy than the 4E' state in P3, As3, Sb3, and Bi3, respectively. All of the features of the main peaks in the photoelectron spectra of the anions observed to date are explained by using calculated geometries, vibrational frequencies, and excitation energies. In addition, a number of peaks are predicted that have not yet been observed experimentally.