HotPatch's hydrophilicity computation is similar to its hydrophobicity computation, but with values multiplied by -1, and no smoothing. Hydrophobicity is computed initially on a by-residue basis: that is, initially all atoms in each residue are assigned a score representing the hydrophobicity value for that residue type, taken from a standard table of free energies of transfer from water to organic solvent (Fauchere, J.L. & Pliska, V. (1983). Eur. J. Med. Chem.-Chem. Ther. 18, 369.)

Lastly, the hydrophobicity values are multiplied by -1, so positive is hydrophilic, negative is hydrophobic. Buried atoms get zero values.