Electronic energy density in chemical reaction systems

摘要

The energy of chemical reaction is visualized in real space using the electronic energy density n_E(r-vector) associated with the electron density n(r-vector).The electronic energy density n_E(r-vector) is decomposed into the kinetic energy density n_T(r-vector),the external potential energy density n_V(r-vector),and the interelectron potential energy density n_W(r-vector).Using the electronic energy density n_E(r-vector) we can pick up any point in a chemical reaction system and find how the electronic energy E is assigned to the selected poing.We can then integrate the electronic energy density n_E(r-vector) in any region R surrounding the point and find out the regional electronic energy E_R to the global E.The kinetic energy density n_T(r-vector) is used to identify the intrinsic shape of the reactants,the electronic transition state,and the reaction products along the course of the chemical reaction coordinate.The intrinsic shape is identified with the electronic interface S that discriminates the region R_D of the electronic drop from the region R_A of the electronic atmosphere in the density distribution of the electron gas.If the R spans the whole space,then the integral gives the total E.The regional electronic energy E_R in tehrmodynamic ensemble is realized in electrochemistry as the intrinsic Volta electric potential O_R and the intrinsic Herring-Nichols work function #PHI#_R.We hacked up first a hydrogen-like atom for which we have analytical exact expressions of the relativistic kinetic energy density n_T_(M) (r-vector) and its nonrelativistic version n_T(r-vector).These expressions are valid for any excited bound states as well as the ground state.Second,we have selected the following five reaction systems and show the figures of the n_T(r-vector) as well as the other energy densities along the intrinsic reaction coordinates:aprotonation reaction to He,addition reactions of HF to C_2H_4 and C_2H_2,hydrogen abstraction reactions of NH_3~(+) from HF and NH_3.Valence electrons possess their unique delocalized drop region remote from those heavily localized drop regions adhered to core electrons.The kinetic energy density n_T(r-vector) and the tension density #tau#(vector)~(S) (r-vector) can vividly demonstrate the formation of the chemical bond.Various basic chemical concepts in these chemical reaction systems have been clearly visualized in real three-dimensional space.