Psi4 QM Fragmentation and Torsion Scanning

This Floe fragments molecules around each rotatable bond and then performs torsion scan on each fragment. Fragments are created around rotatable bonds to allow torsion scans to mimic the energetics of that torsion in the original molecule. Torsion scanning is performed with the OETorsionScan function from the OESzybki Toolkit at a specified resolution (in degrees). This function includes a force field minimization of all internal degrees of freedom except for rotatable torsion in each fragment. Then, a QM optimization is performed with the torsion constrained while all other degrees of freedom are relaxed. Lastly, these torsion scans are used to determine the torsion rules that should be used for each rotatable bond in future conformer generation. There are two outputs from this Floe: First, the fragments as multi-conformer molecules where each conformer represents one angle from the torsion scan. Second, the input (parent) molecules with the torsion rules for conformer generation. The parent output can be used as input for the ‘Psi4 QM Conformer Ensemble’ or Psi4 QM Local Minima Search Floes and the custom torsion rules will be used in the conformer generation step.

Extra Required Parameters

• Input Dataset (data_source) : The dataset(s) to read records from
• Psi4 Energy Field (Field Type: Float) : New field created on torsion scan output to store QM energy at each torsion angle.

  Default: Psi4 Energy (kcal/mol)
• Torsion Rules Output (dataset_out) : Dataset to store records with custom torsion rules, these can be used as input in ‘Psi4 QM Conformer Ensemble’ or Psi4 QM Local Minima Search’ Floes to use the custom torsion rules during conformer generation.

  Default: torsion_rule_output
• Fragment Output (dataset_out) : Dataset to store fragment records with torsion scans.

  Default: fragment_output
• Failure Output (dataset_out) : Dataset to store records which fail during this Floe.

  Default: psi4_fragmentation_failures