Supplementary Information: "Evaluating the use of absolute binding free energy in the fragment optimization process" Included are the ABFE raw free energy samples for multiple replicates (labelled by `run` number) of 18 ligands bound to HSP90. These ligands are originally detailed by Murray et al. (https://doi.org/10.1021/jm100059d). All samples are provided as a set of `.xvg` files as generated by GROMACS 2021 (https://doi.org/10.5281/zenodo.5849961). The `.xvg` files are labelled as dhdl.N.xvg where N represents the �� state the free energy values were sampled from. The `.xvg` files contain both ��H/���� and ��H values, please see the header of each files for more information. Samples detailing the partial decoupling of the ligand from the protein-ligand complex are contained within the `complex` folder. These consist of an orientational restraint addition step (found within the `restraints-xvg` folders), charge annihilation step (found within the `coul-xvg` folders), and Van der Waals decoupling step (found within the `vdw-xvg` folders). Samples detailing the partial decoupling of the ligand from solvent are contained within the `ligand` folder and consist of a charge annihilation step (found within the individual `coul-xvg` folders) and a Van der Waals decoupling step (found within the individual `vdw-xvg` folders).