Ab initio calculations on SCl2 and low-lying cationic states of SCl2+: Franck-Condon simulation of the UV photoelectron spectrum of SCl2

Abstract

states of SCl 2 + at the restricted-spin coupled-cluster single-double plus perturbative triple excitation ͓RCCSD͑T͔͒ level with basis sets of up to the augmented correlation-consistent polarized quintuple-zeta ͓aug-cc-pV͑5+d͒Z͔ quality. Effects of core electron correlation, basis set extension to the complete basis set limit, and relativistic contributions on computed minimum-energy geometrical parameters and/or relative electronic energies were also investigated. RCCSD͑T͒ potential energy functions ͑PEFs͒ were calculated for the X 1 A 1 state of SCl 2 and the low-lying states of SCl 2 + listed above employing the aug-cc-pV͑5+d͒Z basis set. Anharmonic vibrational wave functions of these neutral and cationic states of SCl 2 , and Franck-Condon ͑FC͒ factors of the lowest four one-electron allowed neutral photoionizations were computed employing the RCCSD͑T͒ / aug-cc-pV͑5+d͒Z PEFs. Calculated FC factors with allowance for the Duschinsky rotation and anharmonicity were used to simulate the first four photoelectron ͑PE͒ bands of SCl 2 . The agreement between simulated and observed He I PE spectra reported by Colton et al. ͓J. Electron Spectrosc. Relat. Phenom. 3, 345 ͑1974͔͒ and Solouki et al. ͓Chem. Phys. Lett. 26, 20 ͑1974͔͒ is excellent. However, our FC spectral simulations indicate that the first observed vibrational component in the first PE band of SCl 2 is a "hot" band arising from the SCl 2 + X 2 B 1 ͑0,0,0͒ ← SCl 2 X 1 A 1 ͑1,0,0͒ ionization. Consequently, the experimental adiabatic ionization energy of SCl 2 is revised to 9.55± 0.01 eV, in excellent agreement with results obtained from state-of-the-art ab initio calculations in this work.

Bonding in SCln (n = 1−6): A Quantum Chemical Study

“…Vibrational − and rotational − spectra have been measured. In addition, the ground state of SCl 2 has been studied by electron diffraction, , photoelectron spectroscopy, − and photoionization mass spectrometry. − SCl 2 has also been the subject of high-level RCCSD(T) calculations. − …”