Aim: to reproduce the structural, dynamic and thermodynamic properties of molecules in the condensed phase.

Model: All atom.

Parameterization: Geometric parameters are derived from Quantum Chemical calculations. Partial charges are fitted using multiple Quantum Chemical electrostatic potential energy surfaces. van der Waals parameters are fitted to the density and heat of vaporization of materials at room temperature.

Parameter assignment and corrections: The assignment procedure is physically based and fully automated. There are no special cases. No scaling factors are used to improve the fit to experiment. No corrections are applied to adjust the interaction of atoms in any specific class of molecule.

Approximations: To minimize artefacts the simulation parameters used for parameterization were very conservative. Where possible time saving approximations were eliminated. The van der Waals and electrostatic cutoff was 1.8 nm. Long range electrostatics were treated using either a reaction field approach or lattice sum techniques. A 1.8 nm cutoff eliminates the need for van der Waals tail corrections, switching functions and minimizes the differences between different treatments of long-range electrostatics. The time step was 1 fs. All interactions were calculated every step together with the pair list. The ability to obtain equivalent results was demonstrated across multiple codes.

Thermodynamic properties: ATB topologies are used to predict the solvation free energy in water and simple alkanes for all molecules for which experimentally determined values are available (claimed experimental uncertainty < 4.18 kJ/mol).

Conformational properties: demonstrate that the local minima obtained using ATB parameters matches that obtained from Quantum Chemical calculations.