A single-point gradient calculation of an embedded molecule provides gradients for all cluster atoms. The QM atoms receive contributions from the QM-computed gradients and the LJ potentials (between QM and MM region). All other atoms have gradient contributions from QM point charge gradients and the LJ potentials (only between the single molecule and the QM molecule). The obtained QM/MM gradients are then used to assemble the necessary gradients for optimisations and properties calculations.