Search

The characterization of the nature of bonds in a series of gas-phase all-metal clusters containing the [Al.sub.4] unit attached to an alkaline, alkaline earth, or transition metal is presented. The results suggest that the [Al.sub.4.sup.2-] system is stabilized by the cations [M.sup.}/[M.sup.2} when M is a light alkaline and alkaline earth metal and destabilized by the transition metal cations.

Two different atomic partitioning were used to study atomic charges and delocalization indexes (DIs) for a series of carbonyl compounds. These compounds are comprised of dimethyl ketone, acetaldehyde, acetic acid, methyl acetate, acetamide, methyl vinyl ketone, divinyl ketone, and benzoic acid.

The stability and electron density topology of quinhydrone complex is analyzed by using multiple computational levels. The variations of two- and six-center delocalization indices have shown a small reduction of electron delocalization in the hydroquinone ring upon complex formation.

A comparison of atomic charges is being done using two different partitionings that is one based on the theory of atoms in molecules and second on the Hirshfeld scheme. The difference between the partitionings pertains to how the sigma electron population is distributed among the atoms of the molecule.

Ortiz and Seminario (J. Chem.Phys.2007, 127, 111106/1–3)proposed some years agoa simple and direct approach to obtain I/Vprofiles from the combination of ab initio equilibriumelectronic structure calculations and the uncertainty principle asan alternative or complementary tool to more sophisticated nonequilibriumGreen’s functions methods. In this work, we revisit the fundamentalsof this approach and reformulate accordingly the expression of theelectric current. By analogy to the spontaneous electron decay processin electron transitions, in our revision, the current is calculatedupon the relaxing process from the “polarized” stateinduced by the external electric field to the electronic ground state.The electric current is obtained from the total charge transferredthrough the molecule and the corresponding electronic energy relaxation.The electric current expression proposed is more general comparedwith the previous expression employed by Ortiz and Seminario, wherethe charge variation must be tested among different slabs of atomsat the contact. This new approach has been tested on benzene-1,4-dithiolateattached to different gold clusters that represent the contact withthe electrodes. Analysis of the total electron deformation densityinduced by the external electric voltage and properties associatedwith the electron deformation orbitals supports the conclusions obtainedfrom the I/Vprofiles. [ABSTRACT FROM AUTHOR]