A New Diabatic Potential Energy Matrix for the Two Lowest Electronic States of H₃

A new two-state diabatic potential energy matrix (DPEM) for H₃ has been constructed, based on the fundamental invariant neural network (FI-NN) diabatization method proposed in our previous work Phys. Chem. Chem. Phys. 21, 15040 (2019). In that initial effort, a two-state DPEM was constructed only with a 10 eV energy threshold. The current work aims to expand the energy range and improve the accuracy of DPEM. This is achieved by the utilization of full configuration interaction (FCI) with aug-cc-pVnZ basis sets and complete basis set (CBS) extrapolation. The original dataset is augmented with additional points with higher adiabatic energies, which give rise to a total of 10985 data points. The DPEM constructed in this work now enables accurate representation of adiabatic energies up to 18 eV. Quantum dynamic calculations based on this DPEM are nearly identical to those obtained from benchmark surfaces, which makes it the most accurate DPEM for the H₃ system to date, therefore facilitating detailed exploration of reaction mechanisms at higher collision energies.