# Numerical Simulation of Interaction between Plasma and Azithromycin Based on Molecular Dynamics
## 4 Statistics and Analysis of Simulation Results  
This part analyzes the azithromycin bond formation and bond-breaking with different active particles with the change of their number. According to the molecular structural formula of azithromycin, the number of C-H bonds that can be broken is 72, the number of C-C bonds is 29, and the percentage of C=C bonds is calculated as the percentage of double bonds formed in the original single bond. Moreover, the rate of C=O bonds is calculated as the percentage of double bonds in the original C-O bond. This calculation method is to more intuitively describe the degree of reaction to azithromycin molecules under the action of different active particles. Figure 13 shows the specific number of broken or formed chemical bonds and the variance with multiple groups of samples. It can be seen that the variance of the C-H bond, C=O bond, and C=C bond are minor, while the variance of the C-C bond breakage is significant, as its breakage number is small. If the number of samples continues to increase, this error can be reduced. Figure 12: The decomposition of azithromycin produces Descladinose Azithromycin and L-cladinose. Figure 14 shows the percentage of each chemical bond change in the azithromycin molecule under the action of different active particles. It can be more intuitive to observe the degree of influence by active particles on the whole molecule. The data of the breaking and formation of main chemical bonds is listed in Table 1. The breakage of the C-H bond is almost throughout the entire reaction, and the oxidation reaction and the breaking of various chemical bonds firstly require a dehydrogenation reaction. It can be observed from Figure 14 that the dehydrogenation ability of ozone and reactive oxygen atoms is stronger, while the dehydrogenation ability of the hydroxyl group is weak. When ten active particles were added, the dehydrogenation capacity of ozone was the highest at about 7.08%. Ozone is unstable and can decompose more oxygen atoms to participate in the dehydrogenation reaction. Still, when 20 active particles or more are added, the dehydrogenation capacity of energetic oxygen atoms is the highest, reaching 38.61%. At the same time, the oxygen generated by the decomposition of ozone will react with hydroxyl groups to produce hydrogen peroxide or hydrogen superoxide instead of taking the hydrogen atoms on carbon atoms; that is to say, the products of ozone decomposition will react with the newly formed hydroxyl and other substances so that hydrogen atoms cannot be extracted from the carbon chain exclusively. Therefore, as the number increases, the hydrogen abstraction ability of oxygen atoms is stronger than that of ozone. Because the structure of the hydroxyl group is more stable than the oxygen atoms, its possibility of bonding with the hydrogen atom is not as urgent as oxygen atoms, and the C-H breaking rate is only 10.69%. Figure 13: Changes in chemical bonds in azithromycin molecules. **(a)**: The number of C-H bond breakage varies with the number of reactive groups; **(b)**: The number of C-C bond breakage varies with the number of reactive groups; **(c)**: The number of C=C bond formation varies with the number of reactive groups; **(d)**: The number of C=O bond formation varies with the number of reactive groups. The mean values and the standard deviation in the figures were obtained from 20 independent simulations. The breaking of the C-C bond is partly caused by the movement and impact of the active particles. The other reason is the formation of a large number of C=C bonds. In the C=C bond, it requires the bond and atoms to be in the same plane, so the breakage of the chemical bond occurs when the forces on the ends of the carbon atoms in the azithromycin molecule are not balanced. The C-C fragmentation ability of ozone is the strongest, reaching 11.38%, while the hydroxyl group is only 6.55%.