2. Parameters Fitting: Fit the target parameters of the low-level (LL) Hamiltonian (GFN2-xTB's element-specific parameters in this work) to minimize the discrepancies between the semiempirical and HL-calculated properties. In our scheme these prop-erties are the PES, atomic gradients and electronic density. This step involves fitting the parameters to reproduce the reference data obtained from the HL calculations as closely as possible. The parameter fitting process is iterative, with continuous refinements until the semiempirical QM/MM Hamiltonian provides a satisfactory match with the HL data.