Uncertainties in the diffusion rate of species on interstellar ice and its impact on the chemical abundance in the cold cores

Interstellar dust grains play an important role in the formation of simple and complex molecules in the interstellar medium. On the surface of grains, most of the species are formed when adsorbed lighter species diffuse from one potential well to another and react with other adsorbed species, resulting in the formation of simple or complex molecules. Thus, diffusion of species on grains is a key process for determining the chemical composition of interstellar ices. We present the impact on the chemical evolution of the species in a dense core by considering the uncertainties in the diffusion energy of species adsorbed on grains. The aim of this work is to find the possibility to limit the uncertainties in the abundances (calculated by the modern chemical codes) by identifying the species (with uncertainties in their diffusion energies) which cause the maximum variation in the abundances of a large number of species. These variations in abundances may result in large errors in the simulated abundances predicted by the modern chemical codes. To find the said uncertainties, we ran a number of cases with 2000-10000 simulations in each case and varied the diffusion energies of some or all surface species randomly within a certain range. Next, we calculated Pearson correlation coefficients between the abundances and the ratio of diffusion to the binding energy of adsorbed species. We identified the species that introduce maximum uncertainty in the ice and gas-phase abundances. With these species we ran three sets, with 2000 simulations in each, to quantify the uncertainties they introduce. Here, we will show the abundances of many species in the gas phase and also on the grain surface. We identify key species that produce a large uncertainty in the abundances of other species. We also try to find how we can eliminate the uncertainties in the gas-phase abundances of almost all the species.