Molecular Frame Dipole Moment of Diatomic Molecules within Relativistic Coupled-Cluster Framework: A Comparative Study of Expectation Value vs. Energy Derivative Approach

The ground state molecular frame permanent dipole moment of alkaline earth metal monofluorides and the group-IIB monohydrides have been calculated using two analytic methods: Z-vector method and the linear expectation value method. Results obtained from this methods have been compared with the experimental values and different contributing terms to the total permanent dipole moment have been discussed thoroughly.<br>

Molecular Frame Dipole Moment of Diatomic Molecules within Relativistic Coupled-Cluster Framework: A Comparative Study of Expectation Value vs. Energy Derivative Approach

The ground state molecular frame permanent dipole moment of alkaline earth metal monofluorides and the group-IIB monohydrides have been calculated using two analytic methods: Z-vector method and the linear expectation value method. Results obtained from this methods have been compared with the experimental values and different contributing terms to the total permanent dipole moment have been discussed thoroughly.<br>

Protein Dielectrophoresis: I. Status of Experiments and an Empirical Theory

The dielectrophoresis (DEP) data reported in the literature since 1994 for 22 different globular proteins is examined in detail. Apart from three cases, all of the reported protein DEP experiments employed a gradient field factor ∇ E m 2 that is much smaller (in some instances by many orders of magnitude) than the ~4 × 1021 V2/m3 required, according to current DEP theory, to overcome the dispersive forces associated with Brownian motion. This failing results from the macroscopic Clausius–Mossotti (CM) factor being restricted to the range 1.0 > CM > −0.5. Current DEP theory precludes the protein’s permanent dipole moment (rather than the induced moment) from contributing to the DEP force. Based on the magnitude of the β-dispersion exhibited by globular proteins in the frequency range 1 kHz–50 MHz, an empirically derived molecular version of CM is obtained. This factor varies greatly in magnitude from protein to protein (e.g., ~37,000 for carboxypeptidase; ~190 for phospholipase) and when incorporated into the basic expression for the DEP force brings most of the reported protein DEP above the minimum required to overcome dispersive Brownian thermal effects. We believe this empirically-derived finding validates the theories currently being advanced by Matyushov and co-workers.

π–π-Induced aggregation and single-crystal fluorescence anisotropy of 5,6,10b-triazaacephenanthrylene

The structural origin of absorption and fluorescence anisotropy of the single crystal of the π-conjugated heterocyclic system 5,6,10b-triazaacephenanthrylene, TAAP, is presented in this study. X-ray analysis shows that the crystal framework in the space group P\overline{1} is formed by centrosymmetric dimers of face-to-face mutually oriented TAAP molecules joined by π–π non-covalent interactions. The conformation of the TAAP molecule is stabilized by intramolecular C—H...N(sp 2), N(sp 2)H...π(CN), and C—H...O(sp 2) hydrogen bonds. The presence of weak π–π interactions is confirmed by quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. The analysis of the optical spectra of TAAP in solution and in the solid state does not allow the specification of the aggregation type. DFT calculations for the dimer in the gas phase indicate that the lowest singlet excitation is forbidden by symmetry, suggesting H-type aggregation, even though the overall absorption spectrum is bathochromically shifted as for the J-type. The experimental determination of the permanent dipole moment of a TAAP molecule in 1,4-dioxane solution indicates the presence of the monomer form. The calculated absorption and emission spectra of the crystal in a simple approximation are consistent with the experimentally determined orientation of the absorption and emission transition dipole moments in TAAP single crystals. The electrostatic interaction between monomers with a permanent dipole moment (ca 4 D each) could result in the unusual spectroscopic JH-aggregate behaviour of the TAAP dimer.

Crystal growth and piezoelectric characterization of mechanically stable ZnO nanostructure arrays

The highest piezoelectric performance of ZnO can be achieved by utilizing the piezoelectric operation along the c-axis due to its anisotropic permanent dipole moment.