Automatic Generation of Intermolecular Potential Energy Surfaces

Abstract

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-HO 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.

vdW‐TSSCDS—An automated and global procedure for the computation of stationary points on intermolecular potential energy surfaces

“…The two limiting cases are the rigid approach and the fully flexible ansatz. The former, rigid approach, keeps all intramolecular parameters frozen while allowing intermolecular ones to relax . This approach can provide an upper bound to the interaction energy and it allows for the investigation of intermolecular vibrations.…”

“…The former, rigid approach, keeps all intramolecular parameters frozen while allowing intermolecular ones to relax. [76] This approach can provide an upper bound to the interaction energy and it allows for the investigation of intermolecular vibrations. On the other hand, the fully flexible approach offers a complete description of the interaction energy, the spectroscopy and reactivity of the system AB, but owing to the necessary increase in dimensionality, it is only feasible for small-or medium-sized systems.…”

“…Alternatively, other approaches make use of genetic or evolutionary algorithms in combination with a large variety of different methodologies allowing for the determination of minimum energy structures of molecular clusters . However, to the best of our knowledge, these approaches are restricted to the so‐called rigid monomer approximation in which both monomers are constrained to their equilibrium geometries …”

“…[77][78][79][80][81][82][83][84][85][86][87][88][89][90][91] However, to the best of our knowledge, these approaches are restricted to the so-called rigid monomer approximation in which both monomers are constrained to their equilibrium geometries. [75,76] In this work, we introduce van der Waals TSSCDS (vdW-TSSCDS), a generalization of the TSSCDS procedure which allows for the automated determination of fully relaxed stationary points on the IPES of non-covalently bound complexes. We have applied vdW-TSSCDS to three van der Waals complexes of increasing dimensionality, namely a system in which an atom, a diatom, or triatomic molecule (argon, molecular nitrogen, and water) interacts with a larger fragment, in all cases benzene.…”

A program for automatically predicting supramolecular aggregates and its application to urea and porphin

“…Because this might be very demanding if done systematically on a fine spatial grid with high-accuracy quantum chemical ab initio calculations, methods for creating random sets of aggregate structures [38,39] and for analytically fitting the potential energy hypersurface using few quantum chemical results at carefully selected points on the hypersurface were developed. [40,41] The approach presented in this work follows a middle route: We perform a systematic scan of the potential energy hypersurface with computationally cheap force fields, after which we detect local energy minima from which we select a small but geometrically highly diverse set and, finally, we postoptimize the resulting aggregate geometries with quantum chemical methods. Importantly, we perform the essential step of selecting a small set of aggregate structures from the large set of local minima already prior to the use of quantum chemical methods.…”