Interactions between large molecules pose a puzzle for reference quantum mechanical methods

Quantum Mechanical Aspects of the Halo Puzzle *

An interpretation of the the “halo puzzle” in accelerators based on quantum-like diffraction is given. Comparison between this approach and the others based on classical mechanics equations is exhibited.

Weak Interactions Between Molecules

Explicit formulae are derived for the calculation of dispersion energies between large molecules, at various levels of approximmion. The derivation introduces frequency-dependent polarizabilities (FDPs), whiCh describe the propagation of electron density fluctuat· ions within each of the separate molecules, but avoids the usual multipole expansion. The resultant dispersion energy formula reveal...

Geometry optimization methods for modeling large molecules

Geometry optimization is an essential part of quantum chemical applications. The diversity of the scaling of different methods from linear to exponential implies that there are different requirements for a chosen optimization method. The proposed method aims to meet two requirements, good scaling with size and reliability, which would be a good match for redundant internal coordinate system-bas...

Single-reference ab initio methods for the calculation of excited states of large molecules.

Quantum mechanical methods for enzyme kinetics.

This review discusses methods for the incorporation of quantum mechanical effects into enzyme kinetics simulations in which the enzyme is an explicit part of the model. We emphasize three aspects: (a) use of quantum mechanical electronic structure methods such as molecular orbital theory and density functional theory, usually in conjunction with molecular mechanics; (b) treating vibrational mot...