1) If bulk crystal structures of the clay minerals are calculated, provide complete crystallographic structure information, including cell parameters, space group, and fractional coordinates of the asymmetrical unit. Some attempt should be made to provide uncertainties for these values, especially if molecular dynamics calculations are performed. Note that the positional parameters of atoms reported to two (and sometimes three) places after the decimal often are not of sufficient accuracy to define Si or Al occupancy in tetrahedral sites.

2) Present analytical expressions for the interatomic potentials or energy functions used in the molecular-mechanics simulations. Owing to the variety of analytical functions used in the various molecular modeling computer codes, it is important to state how the electrostatic (charge basis), van der Waals (Lennard-Jones, Buckingham, etc.), and bonded (harmonic, Morse, three body, etc.) energies are evaluated. Energy parameters and partial charges that are not from a previously published forcefield should be tabulated. These concerns are important as most readers of Clays and Clay Minerals are not familiar with the various modeling approaches.

4) Studies involving quantum chemical techniques should present the fundamental equations and the basis of the Hamiltonian expression. Approximations for the method, basis sets, and analytical or numerical techniques should be discussed. Appropriate references describing the details of the quantum methods should be provided.

4) Provide a short summary of the various parameters used in the calculations (energy minimization, molecular dynamics, Monte Carlo methods) so that others may be able to reproduce your results. Ewald parameters, cut-off distances, exclusions, constraints, optimization algorithms, thermostats, stresses, time steps, canonical ensemble type, number of trials, critical energy values, and acceptance criteria should be presented where appropriate.

5) If possible, avoid rigid (or constrained) structures for the clay mineral and any intercalates in the molecular mechanic simulations. Failure of a forcefield to provide a reasonable approximation of the clay portion of the structure when allowed to fully relax at constant pressure indicates an unstable configuration, with the system being far removed from any minimum on the potential-energy surface. A flexible forcefield allows for momentum and energy transfer among all species in molecular dynamics simulations.

6) Simulation studies examining the intercalation of a molecule or ion within the clay should first present the geometry and optimized configuration of the isolated molecule in the gas phase (or in the pure liquid). Separate figures of these results would help for later comparison with the intercalate optimized within the clay interlayer.