Roaming Dynamics of H+C_(2)D_(2) Reaction on Fundamental-Invariant Neural Network Potential Energy Surface

We performed extensive quasiclassical trajectory calculations for the H+C_(2)D_(2)→HD+C_(2)D/D_(2)+C_(2)H reaction based on a recently developed,global and accurate potential energy surface by the fundamental-invariant neural network method.The direct abstraction pathway plays a minor role in the overall reactivity,which can be negligible as compared with the roaming pathways.The acetylenefacilitated roaming pathway dominates the reactivity,with very small contributions from the vinylidene-facilitated roaming.Although the roaming pathways proceed via the short-lived or long-lived complex forming process,the computed branching ratio of product HD to D_(2) is not far away from 2:1,implying roaming dynamics for this reaction is mainly contributed from the long-lived complex-forming process.The resulting angular distributions for the two product channels are also quite different.These computational results give valuable insights into the significance and isotope effects of roaming dynamics in the biomolecular reactions.

Ab initio calculation of the ground and first excited states of the lithium dimer

Based on a high level ab initio calculation which is earned out with the multireference configuration interaction method under the aug-cc-pVXZ(AVXZ)basis sets,X=T,Q,5,the accurate potential energy curves(PECs)of the ground state X^(1)Σ_(g)^(+)and the first excited state A^(1)Σ_(u)^(+)of Li_(2)are constructed.By fitting the ab initio potential energy points with the MurrellSorbie potential function,the analytic potential energy functions(APEFs)are obtained.The molecular bond length at the equilibnum(R_(e)),the potential well depth(D_(e)),and the spectroscopic constants(B_(e),ω_(e),α_(e),andω_(e)χ_(e))for the X^(1)Σ_(g)^(+)state and the A^(1)Σ_(u)^(+)state are deduced from the APEFs.The vibrational energy levels of the two electronic states are obtained by solving the time-independent Schrodmger equation with the Founer gnd Hamiltonian method.All the spectroscopic constants and the vibrational levels agree well with the experimental results.The Franck-Condon factors(FCFs)corresponding to the transitions from the vibrational level(v’=0)of the ground state to the vibrational levels(v"=0-74)of the first excited state have been calculated.The FCF for the vibronic transition of A^(1)Σ_(u)^(+)(v"=0)←X^(1)Σ_(g)^(+)(v’=0)is the strongest.These PECs and corresponding spectroscopic constants provide reliable theoretical references to both the spectroscopic and the molecular dynamic studies of the Li_(2)dimer.