How the molecular face and the interaction vary as H atom approach H2 molecule

Abstract

First, we briefl y introduce the potential acting on one electron in a molecule ( PAEM ). Second, based on PAEM, the molecular intrinsic characteristic contours ( MICC) is defi ned uniquely and intrinsically, and then, the electron density distribution is mapped on the MICC which is called molecular face ( MF ), an identifi cation card, which is an intrinsic characteristic “ face ” or “ fi ngerprint ” for a molecule. Third, the polarization phenomena have been quantitatively demonstrated, i.e., the changing features of the spatial characteristic and the frontier electron density on the MF surface have been shown for reaction H 2 + H → H + H 2, denoted as H1 − H2 + H3 → H1 + H2 − H3, along the linear reaction path, which is compared with those quantities of the reaction H + H → H 2 process. Furthermore, the conversion between the van der Waals interaction and chemical bonding during the process of H1 − H2 + H3 → H1 + H2 − H3 reaction is shown by the PAEM -MO diagram, which provides insight into the characteristic of the interaction between two atoms: At the starting step of the reaction, the interaction between H1 and H2 atoms is chemically bonded, while the interaction between H2 and H3 is van der Waals interaction, and the contour of H2 atom in H 2 molecule does not overlap with that of the H3 atom, which means that the electron interfl ow between H1 and H2 atoms is free and the electron interfl ow between H2 and H3 atoms is blocked by a PAEM barrier or must tunnel the barrier. At the transition state, both the pair of H1 and H2 and the pair of H2 and H3 are chemically bonded.