In the latest versions of CMAQ, we have generally tried to specify unique deposition properties for all gas-phase organic species . You can find the values unique to the species in hlconst.f. You can also refer to the papers where the algorithms were developed. For SOA species, the relative role of solubility and gas-phase deposition depends on volatility (see Figure 5 of Pye et al. 2017) as well as the solubility of the gas-phase species (refer to hlconst values).