The energy of interaction between
molecules is commonly expressed
in terms of four key components: electrostatic, polarization, dispersion,
and exchange-repulsion. Using monomer wave functions to obtain accurate
estimates of electrostatic, polarization, and repulsion energies along
with Grimme’s dispersion corrections, a series of energy models
are derived by fitting to dispersion-corrected DFT energies for a
large number of molecular pairs extracted from organic and inorganic
molecular crystals. The best performing model reproduces B3LYP-D2/6-31G(d,p)
counterpoise-corrected energies with a mean absolute deviation (MAD)
of just over 1 kJ mol<sup>–1</sup> but in considerably less
computation time. It also performs surprisingly well against benchmark
CCSD(T)/CBS energies, with a MAD of 2.5 kJ mol<sup>–1</sup> for a combined data set including Hobza’s X40, S22, A24,
and S66 dimers. Two of these energy models, the most accurate and
the fastest, are expected to find widespread application in investigations
of molecular crystals