Atomic Connectivity Group Contribution Method for Predicting the Phase Transition Properties of Enthalpy and Entropy

Inthis paper, four atomic connectivity group contribution (ACGC)models are developed for predicting the phase transition propertiesof organic compounds. These established ACGC models include atomicadjacent groups (AAG), shape factors (SFs), and atomic connectivityfactors (ACFs), which are used to predict the entropy of fusion (& UDelta;(fus) S), standard enthalpy of vaporization (& UDelta;(vap) H & DEG;), standard enthalpy of sublimation(& UDelta;(sub) H & DEG;), and enthalpy of fusion(& UDelta;(fus) H). Groups are defined as atomicadjacent groups through the relation between the core atom and itsneighbor atoms. Shape factors and atomic connectivity factors areproposed to deal with isomers in the group contribution (GC) method.After the introduction of SFs and ACFs into our models, the mean absoluteerror of the & UDelta;(fus) S, & UDelta;(vap) H & DEG;, & UDelta;(sub) H & DEG;, and & UDelta;(fus) H values for isomersdecreases by 7.97%, 16.57%, 14.33%, and 6.28%, respectively. The & UDelta;(fus) S, & UDelta;(vap) H & DEG;, & UDelta;(sub) H & DEG;, and & UDelta;(fus) H models of ACGC can provide accurate calculationresults with high R (2) values of 0.945,0.991, 0.921, and 0.901. Further, it is proved that ACGC models havegood predictive ability and robustness through external validationand cross validation.