LaREST

LaREST (Lactone Ring-opening Energetics Sorting Tool) is a computational chemistry pipeline for predicting the thermodynamics of lactone ring-opening polymerization reactions.

Given a set of monomer SMILES strings and polymer chain lengths, it computes Boltzmann-averaged enthalpies (H), entropies (S), and free energies (G) by chaining together four levels of theory:

Stage	Tool	Description
1	RDKit + xTB	MMFF conformer generation, ranked by xTB free energy
2	CREST	Conformer/rotamer ensemble exploration (iMTD-GC)
3	CENSO + ORCA	DFT refinement of the ensemble (four sub-stages)
4	CREST entropy	Conformational entropy correction

Two reaction types are supported:

• RER (Ring Equilibrium Reaction) — no initiator; polymer chain only

• ROR (Ring-Opening polymerization Reaction) — includes an initiating alcohol

Final reaction thermodynamics are computed as:

\[\Delta X = \frac{X_\text{polymer} - n \cdot X_\text{monomer} - X_\text{initiator}}{n}\]

where n is the polymer chain length.