In lattice energy models that combine ab initio and empirical components, it is important to ensure
consistency between these components so that meaningful quantitative results are obtained. A
method for deriving parameters of atom-atom repulsion dispersion potentials for crystals, tailored
to different ab initio models is presented. It is based on minimization of the sum of squared de-
viations between experimental and calculated structures and energies. The solution algorithm
is designed to avoid convergence to local minima in the parameter space by combining a deter-
ministic low-discrepancy sequence for the generation of multiple initial parameter guesses with
an efficient local minimization algorithm. The proposed approach is applied to derive transferable
exp-6 potential parameters suitable for use in conjunction with a distributed multipole electrostatics
model derived from isolated molecule charge densities calculated at the M06/6-31G(d,p) level of
theory. Data for hydrocarbons, azahydrocarbons, oxohydrocarbons, organosulphur compounds
and chlorohydrocarbons are used for the estimation. A good fit is achieved for the new set of
parameters with a mean absolute error in sublimation enthalpies of 4.1 kJ/mol and an average
rmsd
15
of 0.31 Å. The parameters are found to perform well on a separate cross-validation set of
39 compounds.