Abstract
Ab initio potential energy surfaces for the ground (X̃1A′) and excited (A˜A′′1) electronic states of HSiBr were obtained by using the single and double excitation coupled-cluster theory with a noniterative perturbation treatment of triple excitations and the multireference configuration interaction with Davidson correction, respectively, employing an augmented correlation-consistent polarized valence quadruple zeta basis set. The calculated vibrational energy levels of HSiBr and DSiBr of the ground and excited electronic states are in excellent agreement with the available experimental band origins. In addition, the absorption and emission spectra of HSiBr and DSiBr were calculated using an efficient single Lanczos propagation method and are in good agreement with the available experimental observations.
Highlights
Silylenes and its halogenated analogs are important reactive intermediates in the chemical vapor deposition of silicon thin films [1] and plasma etching process [2]
The equilibrium geometry of HSiBr at the ground electronic state potential energy surface (PES) was found to be located at RHSi = 2.869 a0, RSiBr = 4.257 a0, and θ = 93.9◦,which is very similar to that of HSiCl [20], except that the Si–Br bond is longer than the Si–Cl bond
It is clear that our equilibrium geometry is in good agreement with the experimental and theoretical values [3, 8, 13]
Summary
Silylenes and its halogenated analogs are important reactive intermediates in the chemical vapor deposition of silicon thin films [1] and plasma etching process [2]. No potential energy surface (PES) has been reported for either the ground or excited electronic state of HSiBr. The lack of reliable PESs will hinder our understanding of the spectroscopy of this important molecule, for highly excited vibrational levels which can be probed by emission spectroscopy. We extend our previous studies on the HGeCl [18], HGeBr [19], and HSiCl [20] systems by reporting accurate ab initio PESs for both the ground (X1A ) and excited (A1A ) electronic states of HSiBr using the coupled cluster singles and doubles with perturbative triples method [CCSD(T)] and the internally contracted multireference configuration interaction method with the (0, 0, 9).
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