Approximating quasi‐particle density functional calculations of small active clusters: Strong electron correlation effects

Abstract

AbstractA new constructive approach for deriving a quantum field chemistry (QFC) is proposed. As a matter of fact, the approach is a direct application of the concept of spontaneously broken symmetry of a free‐electron‐field vacuum to the exact definition of a condensed‐state chemical microstructure. The main idea is to identify the properly modified ground states of the vacuum with ground states of some compact quasi‐molecular systems condensed in a set of “kink”‐bounded molecular {vα} subspaces. Phase transitions of the electron vacuum are as usually expressed in terms of quantum order parameter set {ϕα1(x) = [ρ(x)]1/2 exp(iλα)}, which defines a single electron densities ρα1(x)=nα(x)/Nα (here Nα=∫nα(x) dx) in exact molecule ground states ρα1(x)=|α1(x)|2. The order parameters are obtained by the self‐consistent procedure of minimizing the ground‐state energy Eα=Nαϵα−1(N) for each open molecular “compacton” with respect to the number of electrons Nα and an average single‐electron energy ϵα−1(Nα). Account is taken of topological definitions of the various molecular constituents: atoms, atomic functional groups, molecules, and their clusters. The stability of diverse clusters is investigated by the method of approximating quasi‐particle density functional (AQDF). It gives particular attention to the description of peculiar intermolecular clusters (Mn) composed with single‐atom molecules (M1=A). Such clusters may be used to simulate some active centers that bear the responsibility for strong effects of nonlinearity and dissipation in condensed states. Some results of AQDF‐calculation of small active Rh‐clusters (n=2, 3, 4) are taken under consideration to illustrate that such clusters resemble neither fragments of bulk solids nor molecules in a gas.