A simple test to see if our model can generate new structures is to ask it to generate molecules with transition wavelengths similar to those from the dataset reported by Griffiths et al. Extended Data Fig. shows a representative sample of the molecules generated by the model. As expected, many molecules come from the training set (colored orange in the figure). Importantly, many molecules are not in the training set, and interestingly, some are not even in the PubChem database of known chemicals. In Figure , we show that for the molecules, the transition wavelength is within a mean absolute percentage error of around 10 %. Note that since the GPR model of Griffiths et al. was shown to perform comparable, if not better, to more costly DFT simulations, we chose to use their model to compute the transition wavelengths for the generated molecules.