Conclusions
Combining the atom connection relationship and group contribution method, atomic connectivity group contribution (ACGC) method is proposed. Based on the relationship between core atom and adjacent atoms, a new group defining method is developed. To make the model more accurate, the shape factor is defined. Atomic connectivity factors are defined to describe the position of each group in a molecule based on the relationship between the core atom and other non-hydrogen atoms. Together with the shape factors, most organic isomers can be distinguished. The R 2 ofT c, P c andV c were 0.9891, 0.9887 and 0.9983, respectively. The ARE of T c, P c andV c were 0.94%, 2.35% and 1.34 % respectively. ARE of ACGC models with critical property are smaller than these of AAG and AAGS, which shows that SF and ACF significantly improve the performance of ACGC method. The ACGC model has high accuracy compared to the classical GC model. From the above comparison, we can conclude that ACGC method is accurate and reliable. We screened the data to ensure that each group is present in more than five compounds. SF and ACF can distinguish isomers effectively. Using the same formula, ACGC can accurately calculate the critical properties of organic compounds, which greatly facilitates the prediction and collection of properties of undetectable organic compounds.