To calculate the potential energy, a similar approach to the standalone ReaxFF code is followed with the exception of charge equilibration. The Electronegativity Equalization Method (EEM) used for distributing partial charges requires the solution of a system of linear equations (for details see ) which is solved using preconditioned iterative solvers for large systems . However, since the number of atoms is small for the training set structures, we use a direct LU factorization that is easier to implement and auto-differentiate.