Extensive Theoretical Study on Various Low-Lying Electronic States of Silicon Monochloride Cation Including Spin−Orbit Coupling

Abstract

The potential energy curves of the 23 Omega states generated from the 12 valence Lambda-S states of silicon monochloride cation are calculated for the first time using the internally contracted multireference configuration interaction method with the Davidson correction and entirely uncontracted cc-pV5Z basis set. Spin-orbit coupling is taken into account by the state interaction approach with the full Breit-Pauli Hamiltonian. Very good agreement is achieved between our computed spectroscopic properties and the available experimental data. In particular, the adiabatic excitation energies of the a3Pi(0+) and a3Pi(1) states computed by us are 31,708 and 31,830 cm(-1), respectively, in excellent agreement with the respective experimental values of 31,721 +/- 2 and 31,836 +/- 3 cm(-1). The curve crossings and the predissociation mechanism are investigated. The transition dipole moments are analyzed and the transition properties of the a3Pi(0+)-X1Sigma(0+)+ and a3Pi(1)-X1Sigma(0+)+ transitions are predicted, including the Franck-Condon factors and the radiative lifetimes.

In search of molecular ions for optical cycling: a difficult road

“…124 In SiCl + and SiBr + , the spinorbit interactions are sufficiently large as well and the radiative lifetime estimates of the a 3 Π 0+ and a 3 Π 1 states are on the order of 0.5-5 ms in SiCl + and 50-100 µs in SiBr + . 125,126 However, our estimations of the FCFs within the double-harmonic approximation for the a 3 Π(ν = 0) → X 1 Σ + (ν = 0) transition are only 0.8703 for SiCl + and 0.7158 for SiBr + , suggesting they are not good candidates for optical cycling. To be sure of this determination, a detailed investigation of the optical cycling schemes in these molecules is required with inclusion of triple excitations and spin-orbit coupling effects.…”

Extensive theoretical study on electronically excited states and predissociation mechanisms of sulfur monoxide including spin–orbit coupling

“…[52][53][54] All the calculations are performed in the C 2v subgroup of C 1v point group, and three The selection of active space is crucial in the CASSCF and icMRCI1Q calculations. In our previous studies on the diatomic cations, 55,56 the active space, which consists of eight electrons and eight molecular orbitals (referred to as CAS (8,8)), was shown to be valid. This active space is based on the full valence orbitals with the first outer-shell s orbital being added, and a low-energy valence s orbital being removed.…”

A Theoretical Study on Laser Cooling Feasibility of Group IVA Hydrides XH (X = Si, Ge, Sn, and Pb): The Role of Electronic State Crossing

“…The choice of active space is very important in the CASSCF and MRCI+Q calculations (Liu et al, 2009;Bian, 2011, 2012). The active space of SiH used here consists of ten orbitals corresponding to Si 2p3s3p4p π and H 1s, and is referred to as (11e, 10o), which is carefully chosen to include proper orbitals, and large enough for the present calculations.…”