Calculation of molecular response properties with the second‐order coupled perturbed electron propagator

We present the theory of the electron propagator perturbed by an external electric field and show how it can be used to calculate a variety of one‐electron linear response properties that are accurate through second order in electron correlation. Some illustrative calculations are discussed. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 625–640, 2000     

Electron attachment to homonuclear diatomic molecules

The electron propagator method is applied to the calculation to the electron affinities of some first- and second-row homonuclear diatomic molecules Li₂, Be₂, C₂, F₂, Na₂, Si₂, and Cl₂. Perturbation theory is applied through second order to analyze the results in order to determine the relative importance of correlation and relaxation effects in the binding of the additional electron. © 1993 John Wiley & Sons, Inc.     

Design of low band gap polymers employing density functional theory—hybrid functionals ameliorate band gap problem

Band gaps in solids and excitation energies in finite systems are underestimated significantly if estimated from differences between eigenvalues obtained within the local spin density approximation (LSDA). In this article we present results on 20 small- and medium-sized π-systems which show that HOMO–LUMO energy differences obtained with the B3LYP, B3P86, and B3PW91 functionals are in good agreement with vertical excitation energies from UV-absorption spectra. The improvement is a result of the use of the exact Hartree–Fock exchange with hybrid methods. Negative HOMO energies and negative LUMO energies do not provide good estimates for IPs and EAs. In contrast to Hartree–Fock theory, where IPs are approximated well and EAs are given poorly, DFT hybrid methods underestimate IPs and EAs by about the same amount. LSDA yields reasonable EAs but poor IPs. © 1997 John Wiley & Sons, Inc. J Comput Chem 18 : 1943–1953, 1997     

A smooth permittivity function for Poisson–Boltzmann solvation methods

This work introduces a continuous smooth permittivity function into Poisson–Boltzmann techniques for continuum approaches to modeling the solvation of small molecules and proteins. The permittivity function is derived using a Gaussian method to describe volume exclusion. The new method allows a rigorous determination of solvent forces within a grid‐based technology. The generality of approach is demonstrated by considering a range of applications for small molecules and macromolecules. We also present a very complete statistical analysis of grid errors, and show that the accuracy of our Gaussian‐based method is improved over standard techniques. The method has been implemented in a new code called ZAP, which is freely available to academic institutions. 1 © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 608–640, 2001     

Transition functional schemes for molecular transition energies

Two different transition functionals are used to calculate the first and second ionization potentials of water. The results compare favourably with more costly E _scf results. Methods of dealing with convergence problems are discussed.     

An X-ray absorption spectroscopy study of the local environment of iron in degradable iron–phosphate glasses

Degradable iron–phosphate glasses with the composition of (CaO)_0.30–(Na₂O)_0.20?x–(Fe₂O₃)_x–(P₂O₅)_0.50, x = 0.01–0.05, were studied by Fe K-edge X-ray absorption spectroscopy (both near-edge, XANES, and extended, EXAFS). The addition of up to 5 mol% iron oxide is known to enhance the durability of the phosphate glass while maintaining biocompatibility. The results from the two techniques used here both show that iron is in the Fe(III) oxidation state and has octahedral coordination. This suggests that Fe is cross-linking the phosphate chains and therefore strengthening the network structure, resulting improved chemical durability of the glasses.     

Electrochemical and photophysical properties of a chemically modified electrode

A surface extinction coefficient for an inorganic complex, bis(2,3′-bipyridine)(2,2′-bipyridine-4,4′-dicarboxylato) ruthenium(II), immobilised on a transparent electrode has been determined for the first time, and demonstrated to be significnatly larger than that of its analogue in homogeneous solution. The first observation of a formal redox potential, for an immobilised complex, which is sharply dependent upon the extent of surface coverage is also reported.     

Approximate energy expression in the calculation of photoelectron transition energies

The possibilities of using approximate self-consistent field energy functionals to reduce computation required in calculating photoelectron transition energies is examined. Numerical results for the H₂O molecule indicate that this is possible without unacceptable deterioration in accuracy of results in favourable cases.