Following our previous work, 3 a temperature-assisted minimum-energy structure search is carried out: first, classical molecular dynamics (MD) simulations at 300 K using General Amber Force Field (GAFF) as implemented in the GULP code 11-13 is performed for 10 ns in canonical ensemble. The atomic charges are calculated using the RESP method 14 at density functional theory (DFT) level employing the sphere sampling of the fitting points for molecular structures 15 together with the REPEAT method. A time step of 0.5 fs is considered in all simulations while the temperature is controlled by a Nosé-Hoover thermostat. 17,18 For each system, 10 uncorrelated snapshots were extracted from the classical MD trajectories, roughly every 1 ns. Afterwards, minimum-energy structures are obtained through geometry optimizations at DFT level.