X-ray analysis of the influence of various nucleating agents on the crystallinity of poly-α-butene

The influence of various nucleating agents on the crystallinity of poly-α-butene form I has been studied. The nucleating agents were: adipic acid, salicylic acid, p-aminobenzoic acid, sodium benzoate and sorbic acid; their influences on the lattice parameters, degree of crystallinity, size of crystallites and texture have been examined. The analysis was carried out by wide-angle X-ray diffraction. The relative degrees of crystallinity in poly-α-butene samples containing nucleating agents were measured using the Hermans-Weidinger procedure; in order to obtain the size of crystallites, the Debye-Scherrer method was applied. The lattice parameters show no change but the relative degree of crystallinity, the size of crystallites and their texture depend on the nucleating agent used.     

Anisotropic Electron Conductance Driven by Reaction Byproducts on a Porous Network of Dibromobenzothiadiazole on Cu(110)

Efficiency in charge‐transport is a fundamental but demanding prerequisite to allow better exploitation of molecular functionalities in organic electronics and energy‐conversion systems. Here, we report on a mechanism that enables a one‐dimensional conductance structure by connecting discrete molecular states at 2.1 eV through the pores of a metal–organic network on Cu(110). Two adjacent, periodic and isoenergetic contributions, namely a molecular resonance and the confined surface‐state, add‐up leading to anisotropic structures, as channels, observable in real‐space conductance images. The adsorption configurations of Br atoms, inorganic byproduct of the redox‐reacted 4,7‐dibromobenzo[c]‐1,2,5‐thiadiazole (2Br‐BTD) molecules on the copper surface, drive the confinement of the Cu surface state within the pores and critically control the channel continuity. Small displacements of the Br atoms change the local surface potential misaligning the energy levels. This work visualizes the effect of order‐disorder transitions caused by the movement of single atoms in the electronic properties of two‐dimensional organic networks.     

Evaluation of screened nuclear attraction and electron repulsion molecular integrals over Gaussian basis functions

Analytical solutions to the Yukawa-like screened Coulomb nuclear attraction and electron repulsion molecular basic integrals, as well as to the basic integrals required to compute the virial coefficient, over Gaussian basis functions, are derived and cast into a practical closed form, suitable to interface with modern codes for the calculation of molecular electronic structure. © 1997 John Wiley & Sons, Inc.     

Closed‐form analytical solutions for the calculation of the moments of the molecular electron density

Moments of the molecular electron density can be related directly to several experimental observables, but formerly they have only been accurately calculated through methods which lack consistency with standard quantum chemical methods. Here we report analytical solutions to the basic molecular integrals required to compute the moments of the molecular electron charge density over Gaussian basis functions. These are derived and cast into a practical closed form, suitable to interface with modern codes for the calculation of the molecular electronic structure. Illustrative calculations for the hydrogen molecule, at both the Hartree–Fock and the full configuration interaction levels of theory, are shown and discussed in connection with observables linked directly to some of the calculated moments. This revised version was published online in July 2006 with corrections to the Cover Date.     

The evaluation of electronic extracule and intracule densities and related probability functions in terms of Gaussian basis functions

The evaluation of the basic two-electron integrals involved in the calculation of extracule and intracule densities is described. Expressions are given for the evaluation of the related spherically averaged, longitudinal, and transverse probability functions from wave functions constructed from Gaussian basis sets. All results are expressed in closed analytical forms which are suited to efficient coding. Given that certain pair densities can be related to experimental scattering cross sections, the formulae reported herein will facilitate further comparison between experiment and theory and lead to a more comprehensive understanding of the electronic structures of molecules.