Theoretical Study on the Excited Electronic States of CHCl: Application to Photodissociation at 193 nm

Abstract

We present herein a high-level ab initio study on the electronic excited states of CHCl using the internally contracted multireference configuration interaction method including Davidson correction (icMRCI+Q). A total of 13 electronic states with energy of up to 7 eV have been investigated. The vertical transition energies, oscillator strengths, electron configurations, and transitions of the electronic states of CHCl have been calculated at the icMRCI+Q/aug-cc-pv(5+d)Z level. The potential energy curves of the electronic states have been studied along the H-C-Cl angle, the C-H bond length, and the C-Cl bond length, respectively. Our theoretical study has provided comprehensive information for understanding the interaction and the behavior of the electronic excited states of CHCl. In particular, the excited state involved in the 193 nm photodissociation as well as the corresponding dissociation dynamics have been discussed on the basis of our calculation results. The present study should shed more light on the photochemistry of CHCl in the ultraviolet region.

Mountaineering Strategy to Excited States: Highly Accurate Energies and Benchmarks for Exotic Molecules and Radicals

“…For these three compounds, the SCI calculations deliver values very close to the CC estimates. For HCCl, a MRCI+Q/quintuple-ζ vertical transition energy, corrected for ground-state ZPVE effects, of 1.68 eV was recently reported . Given that the ZPVE energy at the MP2/ aug -cc-pVTZ level is 0.31 eV, our TBE is basically equivalent to this recent result.…”

A Mountaineering Strategy to Excited States: Highly Accurate Energies and Benchmarks for Medium Sized Molecules

“…For HCCl, a MRCI+Q/quintuple-ζ vertical transition energy, corrected for ground-state ZPVE effects, of 1.68 eV was recently reported. 96 Given that the ZPVE energy at the MP2/aug-cc-pVTZ level is 0.31 eV, our TBE is basically equivalent to this recent result. For HSiF, the most accurate previous estimate of the excitation energy is likely the CC3/aug-cc-pVTZ 3.07 eV value, 97 which is extremely close to our TBE.…”

An ab initio study on the electronic excited states and photodissociation mechanism of bromocarbene molecule

“…The mechanism of the CHBr in the ultraviolet region is similar to that of other triatomic halocarbenes CHCl/CHI reported in theoretical and experimental investigations. 9,57,58 We show that both SOC and non-adiabatic interaction play important roles in photodissocaiton of the CHBr molecule. Our theoretical calculations provide an important basis for comprehending complicated behavior and dynamics between the states of halogenated carbenes and may serve as a reference for further experimental research.…”

“…In recent years, based on high-resolution laser spectroscopy and high-precision quantitative calculation methods, researchers have conducted numerous studies on CXY molecules, e.g. , monohalogenated carbenes CHF 6,7 /CHCl 8,9 /CHBr 10,11 /CHI 12–14 and dihalogenated carbenes CF 2 15,16 /CCl 2 17,18 /CBr 2 19,20 /CI 2 21 /CFCl 22,23 /CFBr, 24–26 which provide valuable information on the electronic states of the triatomic halocarbenes, such as the singlet–triplet energy gap, spectroscopic constants, photodissociation dynamics and so on.…”