RDKitConverter benchmark

This repository benchmarks the ability of MDAnalysis’ RDKitConverter to infer bond orders and charges from molecules with all hydrogens explicit.


Requires conda (or mamba) on a Linux machine.

Start by cloning this repository:

git clone https://github.com/MDAnalysis/RDKitConverter-benchmark.git
cd RDKitConverter-benchmark

Then install the python dependencies with make install:

# to speed things up you can use mamba:
make install CONDA=mamba

This will create a separate conda environment called rdkitconverter.

Finally, run the benchmark:


Run make help to get a list of available commands.

The results are available in the results/ directory:

  • results.json, a JSON file listing all the necessary information
  • failed_molecules.smi, a SMILES file containing the molecules that failed the test
  • failed_molecules.html, an interactive table displaying the failed molecules


The benchmark will fetch ChEMBL 30 as an SDF file and process the molecules the following way:

  • Discard molecules that could not be read or sanitized by RDKit
  • Keep only the largest fragment
  • Keep only molecules with 2 to 50 heavy atoms
  • Discard molecules with radicals
  • Drop duplicate molecules based on their InchiKey

Once the data is fetched and standardized, the benchmark can be run. The benchmark will start by preparing a “reduced” version of the molecule by removing bond orders and formal charges. This is done to mimic the minimal information available in most topology files for MD simulations.

The RDKitConverter might give different results depending on the order of atoms in the molecule. For that reason, the benchmark will enumerate reordered version of the molecule so that each atom appears in the first position once. This is done by reading a SMILES of the molecule rooted at the given atom, so that the other atoms of the molecule are reordered in a realistic way.

Finally, the reordered “reduced” molecule goes through the MDAnalysis code responsible for inferring bond orders and formal charges.

During the enumeration of reordered molecules, if any of the inferred molecules fails to match with the original molecule or one of its resonance structures, the whole test fails for that molecule.

Prototype code:

def benchmark_mol(reference_mol):
    reduced_mol = remove_bond_orders_and_charges(reference_mol)
    for mol in enumerate_reordered_mol(reduced_mol):
        mol = infer_bond_orders_and_charges(mol)
        valid = is_same_mol_or_resonance_structure(mol, reference_mol)
        if not valid:
            return "FAILED"
    return "SUCCESS"


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