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tokens: considered at the highest density ( ρ max ), i.e., at t = t coll . From this stage onward, we have assumed that the temperature of the dust and the gas is the same. Thus, we have considered a negative slope for T gas for the collapsing phase. Throughout the first phase, the visual extinction parameter is considered to be constantly increasing from to finally at in t = t coll . Second phase: the second phase of the simulation corresponds to a warm-up phase. Since G10 is a high-mass star-forming region, we consider a moderate warm-up timescale ( t w ) 5 × 10 4 yr (Garrod 2013 ). Therefore, during this short period, the temperature of the cloud from T ice can reach the highest hot-core temperature T max . The density, temperature, and visual extinction parameter remain constant at ρ max , T max , and , respectively. Third phase: this phase belongs to the post-warm-up time. Here, we have considered a post-warm-up timescale ( t pw ) of 10 5 yr, so the total simulation time is . The parameters such as density and visual extinction are assumed to be the same as they were in the warm-up phase. The temperature of the cloud is kept at T max throughout the last phase. 4.2. Binding Energies and Reaction Pathways To study the desorption energy (BE) and reaction pathways of three peptide-bond-like species HNCO, NH 2 CHO, and CH 3 NCO and their isomers/precursors, we use the Gaussian 09 suite of programs (Frisch et al. 2013 ). Recently, Das et al. ( 2018 ) made an extensive effort to estimate the BE of 100 interstellar species on water-ice surfaces by applying a quantum chemical approach and compared their values with the available experimental results. They found that on average, the computed BE shows a larger deviation from experiments when they considered a single water molecule as a substrate. The deviation is minimal when they used pentamer or hexamer configurations of water clusters. They provided a scaling factor for the extrapolation as the computation was performed with smaller water structures. We carry out a quantum chemical study to find out the BEs of the three peptide-bond-related species considered in this work along with their potentially observable isomers. To estimate the BEs of these species, we have used a similar method and basis set (MP2/aug-cc-pVDZ) as mentioned in Sil et al. ( 2017 ) and Das et al. ( 2018 ). Our calculated BE values are given in Figure 7 . For some cases, we have found multiple probable sites for the adsorption and thus obtained multiple BE values. In that case, we take the average of the multiple BEs. Calculated BEs with a single water molecule are then scaled up by a factor of 1.416 (Das et al. 2018 ) to have a realistic estimation. Additionally, in Figure 7 we present the BE values for some of these species with a hexamer configuration of water clusters. Since the BEs with the pentamer/hexamer configurations show minimum deviation (Das et al. 2018 ), one can use these BE values in the model without scaling. We are