Globally accurate potential energy surface for the ground-state HCS(X2A′) and its use in reaction dynamics

Abstract

A globally accurate many-body expansion potential energy surface is reported for HCS(X2A′) by fitting a wealth of accurate ab initio energies calculated at the multireference configuration interaction level using aug-cc-pVQZ and aug-cc-pV5Z basis sets via extrapolation to the complete basis set limit. The topographical features of the present potential energy surface are examined in detail and is in good agreement with the raw ab initio results, as well as other theoretical results available in literatures. By utilizing the potential energy surface of HCS(X2A′), the dynamic studies of the C(3P) + SH(X2Π) → H(2S) + CS(X1∑+) reaction has been carried out using quasi-classical trajectory method.

Globally Accurate Potential Energy Surface for HCS(A2A″) by Extrapolation to the Complete Basis Set Limit

“…Moreover, the C( 3 P) + SH(X 2 Π) → H( 2 S) + CS(a 3 Π) reaction is exoergic by ∼0.204 eV, while the exothermicity is ∼3.66 eV for the ground state. 21 It should be noticed that the MEP on this PES presented has a low barrier in the H( 2 S) + CS(a 3 Π) asymptote at ∠CSH = 90°, which can be assigned to the saddle point (SP1) connecting the H( 2 S) + CS(a 3 Π) asymptote. Figure 6 displays the capture time which provides a chance to further study the reaction mechanism.…”

“…It can be seen that there exists a deep well for the C­( 3 P) + SH­(X 2 Π) → H­( 2 S) + CS­(a 3 Π) reaction, with a calculated well depth of 3.076 eV at ∠CSH = 90° relative to C­( 3 P) + SH­(X 2 Π). Moreover, the C­( 3 P) + SH­(X 2 Π) → H­( 2 S) + CS­(a 3 Π) reaction is exoergic by ∼0.204 eV, while the exothermicity is ∼3.66 eV for the ground state . It should be noticed that the MEP on this PES presented has a low barrier in the H­( 2 S) + CS­(a 3 Π) asymptote at ∠CSH = 90°, which can be assigned to the saddle point (SP1) connecting the H­( 2 S) + CS­(a 3 Π) asymptote.…”

“…The linear parameters a i ( i = 1, 2, ..., 9) and the nonlinear parameters β i ( i = 1, 2) in eqs and are acquried by fitting the ab initio potential energies of the diatoms. Here, the accurate PEC of CH­(X 2 Π) used is from ref and the ones of CS­(a 3 Π) and SH­(X 2 Π) are from the present least-squares fit to CBS energy points. The values of parameters used to model the diatomic potentials are gathered in Table S1 of the Supporting Information.…”

“…20 Most recently, a globally accurate many-body expansion (MBE) PES for the ground state of HCS(X 2 A′) was constructed by us through fitting plenty of precise complete basis set (CBS) energy points. 21 On the basis of the PES, the dynamic studies of the C( 3 P) + SH(X 2 Π) reaction were also carried out using the quasi-classical trajectory (QCT) method.…”

“…The spin–orbit constants, dipole moments, and carbon–sulfur distances for HC n S ( n = 1–12) in the 2 Π state were calculated by using the Hartree–Fock (HF), complete active space self-consistent field (CASSCF), and MRCI methods with different basis sets . Most recently, a globally accurate many-body expansion (MBE) PES for the ground state of HCS­(X 2 A′) was constructed by us through fitting plenty of precise complete basis set (CBS) energy points . On the basis of the PES, the dynamic studies of the C­( 3 P) + SH­(X 2 Π) reaction were also carried out using the quasi-classical trajectory (QCT) method.…”