Supplimentary Figure 1: 2D PES (in kcal/mol) of the dihedral angles (in radians) of isopentenyl phosphate at the HF/6-31G(d) level of theory. Supplimentary Figure 2: 2D PES (in kcal/mol) of the dihedral angles (in radians) of diisopropyl fluorophosphate at the HF/6-31G(d) level of theory. Supplimentary Figure 3: 2D PES (in kcal/mol) of the dihedral angles (in radians) of the STAT 1 ligand at the HF/6-31G(d) level of theory. Supplimentary Figure 4: 2D PES (in kcal/mol) of the dihedral angles (in radians) of leucine dipeptide at the HF/6-31G(d) level of theory. Compound Dihedral Methyl L-lactate c3-c-os-c3 c3-c-os-c3 c3-c-os-c3 c3-c3-c-os c3-c3-c-os c3-c3-c-os c2-c3-c3-os c2-c3-c3-os c2-c3-c3-os c3-c3-os-p5 c3-c3-os-p5 c3-c3-os-p5 p5-os-c3-c3 p5-os-c3-c3 p5-os-c3-c3 os-p5-os-c3 os-p5-os-c3 os-p5-os-c3 C-N-CT-C C-N-CT-C N-CT-C-N N-CT-C-N n2-n-c-ca n2-n-c-ca cd-cc-ce-n2 cd-cc-ce-n2 c-cc-ce-n2 c-cc-ce-n2 cc-ce-n2-n cc-ce-n2-n Isopentenyl phosphate Diisopropyl fluorophosphate Leucine dipeptide STAT5 Ligand 1 STAT5 Ligand 2 𝑉𝑑 (kcal/mol) 0.78 2.547 -0.701 0.286 1.077 -0.379 -2.835 2.085 -0.923 1.299 0.298 1.201 18.924 4.322 -0.059 -1.605 0.799 -0.648 -2.932 -2.251 0.722 1.344 2.418 2.376 -1.706 -0.099 4.785 2.222 -1.195 9.11 𝜓𝑑 (degrees) Multiplicity 176.343 176.257 199.047 208.641 100.298 195.37 38.273 33.615 50.217 80.272 120.846 -44.462 -158.005 159.185 110.445 58.662 -52.456 -25.164 149.444 240.79 308.88 213.928 166.884 176.693 173.927 224.584 172.919 161.804 181.14 178.084 Supplimentary Table 1: Dihedral terms derived using MC with importance sampling. Atom types for the dihedrals are written in terms of the GAFF. 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 1 2 1 2 1 2 1 2 1 2