To obtain accurate energies and forces, 1000 configurations are randomly selected from a 40-ps ReaxFF MD simulation, and high-level DFT calculations are further conducted. DFT calculations were performed using the CP2K package . Core electrons are treated using Goedecker-Teter-Hutter (GTH) pseudopotentials and the Perdew Burke Ernzerhof generalized gradient approximation method . The Grimme DFT-D3 method is used to account for dispersion interactions. A double-zeta Gaussian basis set plus polarization (DZVP-MOLOPT) is considered. In addition to MD simulations, configurations are also obtained using active learning sampling as implemented in the DP-GEN package with a temperature range from 300 to 4000 K. With the above method, an ab initio database with energy and force information is constructed to train the NN potential.