ATOM-BOND ELECTRONEGATIVITY EQUALIZATION METHOD .1. CALCULATION OF THE CHARGE-DISTRIBUTION IN LARGE MOLECULES

On the basis of the principle of electronegativity equalization and de nsity-functional theory, an atom-bond electronegativity equalization m ethod has been developed for the calculation of the charge distributio n in large molecules that are connectivity and geometry dependent. The effective electronegativities of an atom and a bond in a molecule are derived and given by equations that contain respective electronegativ ities, hardness terms, and contributions that come from other atomic a nd bond charges. The parameters A, B, C, and D are the valence-state e lectronegativity and the valence-state hardnesses. They are obtained b y calibrating through calculations of more than 100 model molecules an d are transferable and consistently usable. The atom-bond electronegat ivity equalization method is tested through calculation of the charge distributions in several large organic molecules, It has been shown th at there is a very good agreement between the results obtained by the atom-bond electronegativity equalization method and those obtained by the corresponding ab initio quantum chemical calculations.