Calculating theoretical octane numbers of various petroleum derivatives using quantum mechanical DFT methods

Abstract

This research included calculating the octane number of a group of chemical compounds using the (DFT) method by using multiple regression analysis of the relationship between the practical octane number values with the theoretically calculated physical variables, where a number of variables were calculated including the calculation of energy functions, including the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LOMO), hardness (η), chemical potential (µ), and spherical electrophilic index (W), and the thermodynamic functions (∆G, ∆H, ∆S, ∆E) and dipole moment were calculated. They were evaluated from the correlation coefficient relationship (R2). Through the four-way statistical analysis, we obtained the best correlation coefficient for the variables calculated using the DFT method, where (R2) showed the highest values for the following variables: (∆E+HOMO+∆G+µ) (R2=0.793) (∆S+ LOMO + ∆G +W) (R2=0.753). Through the single and multiple statistical analysis, the most influential variable on the octane number values is (HOMO).