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Problem Statement

A wide range of density functional methods and a large number of basis sets are available to derive the electronic structure and properties of molecules. Estimating the accuracy of calculation method for desired properties, and choosing a method with a low computational cost, need a comprehensive evaluation of the methods on a test set of representative molecules. Conformational energies and a set of torsion profiles have been benchmarked before by Lee-Ping (link) and B3LYP-D3BJ/DZVP level of theory has been chosen for building OpenFF force fields. There are still some unanswered questions on

• whether this is a good choice for charged molecules?

• any density-driven or delocalization errors creep up in torsion scans as shown in Burke’s papers (https://dx.doi.org/10.1021/acs.jpclett.1c00426 )

• how good it is in describing problematic chemistries, like

  • biaryl torsion barriers (http://dx.doi.org/10.1021/ct5004725 ).

  • chalcogen, halogen interactions (http://doi.org/10.1021/acs.jctc.1c00006 ). Strong polarizability from these elements induce strong dispersion interactions, and there is a need to check on how the current level of theory is performing and whether the dispersion corrections are good enough to compensate for that.

  • and non covalent interactions in general.

• transferability of accuracy shown in density functional benchmarks with larger basis sets (from literature) to smaller basis sets?

Scope

Must have:

• Accuracy of torsional profiles, accuracy of dipole and quadrupole moments, comparison of computational performance of methods

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Timeline

Milestones and deadlines

Reference materials

• Lee-Ping’s benchmark of conformational energies on MPCONF196 set and a select set of 15 torsion profiles (link), and discussion about DZVP (link)

• Lee-Ping’s benchmark with the new basis set configuration that addresses the Iodine issue raised by Bill Swope (link).

• Some initial summary on current DFT benchmarks from literature (link)
  

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