Triple Cluster Research Articles

The treatment of triple excitations within the coupled cluster description of molecular electronic structure

Equations for the determination of the cluster coefficients in a full coupled cluster theory involving single, double, and triple cluster operators with respect to an independent particle reference, expressible as a single determinant of spin-orbitals, are derived. The resulting wave operator is full, or untruncated, consistent with the choice of cluster operator truncation and the requirements of the connected cluster theorem. A time-independent diagrammatic approach, based on second quantization and the Wick theorem, is employed. Final equations are presented that avoid the construction of rank three intermediary tensors. The model is seen to be computationally viable, size-extensive, high-level description of electron correlation in small polyatomic molecules.

Synthesis and characterisation of a triple cluster of gold and boron

Reaction of B10H14 with Et3PAuMe affords the triple cluster [(H12B10Au)(AuPEt3)4(AuB10H12)], and with Cy3PAuMe (CY = cyclohexyl) the substituted complex [Cy3PAu(B10H13)] is isolated; a mechanism for the formation of the triple cluster is proposed.

Cluster Probabilities for Simple Lattices Containing Two Impurities

Concentration-dependent probabilities for flnding one of two kinds of impurities in a single, pair, or triple cluster within a simple cubic, body-centered-cubic, face-centered-cubic, or hexagonal-close-packed lattice are given as polynomials for which tabulated values are readily available. Both nearest-neighbor interactions and next-nearest-neighbor interactions between foreign impurities in random distribution within the lattice are each separately treated. Graphical comparisons of the results indicate that the effect of introducing an additional impurity is similar to that of including next-nearest-neighbor interactions. In both cases cluster probabilities are decreased.