New diabatic potential energy surfaces of the NaH2 system and dynamics studies for the Na(3p) + H2 → NaH + H reaction

Abstract The Na(3p) + H 2 (X 1 Σ g + ) → NaH(X 1 Σ + ) + H( 2 S) reaction plays an important role in the field of diabatic reaction dynamics. A set of new diabatic potential energy surfaces (PESs) of the NaH 2 system are structured, which include the diabatic coupling between the lowest two adiabatic states. The electronic structure calculations are performed on the multi-reference configuration interaction level with the cc-pwCVQZ and aug-cc-PVQZ basis sets for Na and H atoms. 32402 geometries are chosen to construct the diabatic data by a unitary transformation based on the molecular property method. The diabatic matrix elements of $${{\boldsymbol{V}}}_{{\bf{11}}}^{{\boldsymbol{d}}}$$ V 11 d , $${{\boldsymbol{V}}}_{{\bf{22}}}^{{\boldsymbol{d}}}$$ V 22 d and $${{\boldsymbol{V}}}_{{\bf{12}}}^{{\boldsymbol{d}}}$$ V 12 d ( $${{\boldsymbol{V}}}_{{\bf{21}}}^{{\boldsymbol{d}}}$$ V 21 d ) are fitted by the artificial neural network model. The spectroscopic constants of diatoms obtained from the present PESs are consistent with the experimental data. The topographical and intersection characteristics of the $${{\boldsymbol{V}}}_{{\bf{11}}}^{{\boldsymbol{d}}}$$ V 11 d and $${{\boldsymbol{V}}}_{{\bf{22}}}^{{\boldsymbol{d}}}$$ V 22 d surfaces are discussed. Based on the new PESs, the time-dependent quantum wave packet calculations are carried out to study the reaction mechanism of the title reaction in detail.