where λ is the computed absorption wavelength of the molecule, λ t is the target wavelength, and σ is 50 nm. The GA searches are terminated if the top score in the population is within 0.01 of the maximum possible score of 2.0. The absorption wavelength and oscillator strength is computed using the xTB-sTDA method based on a low-energy molecular structure computed using the MMFF94 force field as implemented in RDKit. The low-energy structure is computed by generating and energy-minimising 20 random conformations using RDKit and choosing the conformer with the lowest MMFF94 energy. The molecules for the initial population are chosen randomly from the first 1000 molecules in 250,000-molecule subset of the ZINC data base that we have used previously. Molecules that absorbed within 100 nm of the target wavelength were excluded from the initial initial population. The goal of these simulations is to illustrate the use of GAs with a scoring function that has a complex dependence on the molecular structure and a target property with multiple solutions, not to find stable, synthetically accessible molecules for experimental testing. The results for 40 50-generation GA searches with a population size of 20 are shown in Figure . The success rates are 100% and 97% for 400 and 600 nm, while only 30% for 200 nm. For 400 and 600 nm, the median number of generations needed to find to find a molecule with the target property is 6 and 20 generations, respectively, which corresponds to screening only 120 and 400 different molecules. While the success rate is comparatively low for 200 nm (requiring up to 13,000 molecule evaluations) it is still impressive given the small population size, initially constructed from randomly chosen molecules (i.e. no pre-screening like for rediscovery). Inspection of the molecules (Figure and Figures ) show that, as expected, they are all different. Thus, there are many molecules in chemical space that satisfy the search criterion with, presumably, many different paths leading to each target, as shown for rediscovery, which increases the chances of success (Figure )).