Automatic Generation of Intermolecular Potential Energy Surfaces

A method is developed
for automatic generation of intermolecular
two-body, rigid-monomer potential energy surfaces based on symmetry-adapted
perturbation theory (SAPT). It is also possible to substitute SAPT
interaction energies by values computed using sufficiently high-level
supermolecular methods. The long-range component of the potential
is obtained from a rigorous asymptotic expansion with ab initio computed coefficients which seamlessly connects to SAPT interaction
energies at large separations. An accompanying software package has
been developed and tested successfully on eight systems ranging in
size from the Cl––H2O dimer to
the cyclotrimethylene trinitramine dimer containing 42 atoms total.
The potentials have a typical fit error of about 0.2 kcal/mol in the
negative energy region. The accuracy may be further improved by including
off-atomic sites or increasing their number. All aspects of potential
development were designed to work reliably on a broad range of systems
with no human intervention.