Threshold density for electron self-localization in gaseous H2

There is a revamped interest in the transport properties of quasi-free electrons in dense and cold hydrogen gas because it has recently been shown that multiple scattering effects modify their drift mobility in the same way as they do in helium and neon gases. Owing to the similarities in the electron-atom/molecule scattering cross sections, there is the possibility that also in hydrogen, electrons self-localize in bubbles as they do in dense gaseous helium and neon and in their liquids. A very scant number of experiments suggest that this may happen. In this paper, we investigate this possibility by numerically carrying out the prediction of the optimum fluctuation model. We show that electron self-localization is a very likely process and that the model accurately predicts the density at which quasi-free electrons and electron bubbles coexist in equal proportions, as inferred from the experiments.