Figure 5.

(A) The hydrogen bonding energy is derived from the distribution of d_HA, θ_DA, θ_HX by using the statistical energy function. P_obs is the observation frequencies; P_ran is the random frequencies; D: Donor atom; H: Hydrogen atom; A: Acceptor atom; X: The heavy atom bonded with A. (B) The constraints energy is of the spring potential if a definite distance is given as the constraint, otherwise it is –k from d₁ to d₂ if the range is given. k is calculated by $\frac{1}{2}{\left|d_1-d_2\right|}^2-1$. The receptor is colored by red and the ligand is colored by blue. d₁ and d₂ are the lower and the upper bound of the user-provided distance range.