From this fit, one can now infer the probability of finding the vapor-electrolyte interface at a distance D x from the electrode by integrating the fitted distribution in an interval between D = 0 and D = D x , and normalizing it by the total integral. The probability of finding a phase α (vapor or electrolyte) at a certain distance from the electrode equals the volume fraction φ α averaged over all positions with that distance to the electrode. The volume fraction of the electrolyte φ el can be expressed by integrating Eq. 1.