User-specified tolerance values y tol are provided to Chimera which indicate objective value thresholds at which the user is satisfied (e.g., one may want to generate a molecule with a QED of at least 0.6, before prioritizing optimizing its solubility). Whether or not some measured value of the i th objective function y i satisfies its corresponding tolerance can be indicated by the Heaviside function, Θ y tol i -y i = 0 if y i ≥ y tol i and 1 if y i < y tol i . Alternatively, discontinuities in the cumulative function can be avoided by utilizing a smooth logistic function approximation to Θ, parameterized by smoothing parameter τ , θ y tol i -y i = 1 + exp -