Main research interests – David L. Cooper – See: publications

• Theoretical studies of small molecule and of molecular processes
• Other research interests

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Theoretical studies of small molecules and of molecular processes

Concepts taken from electronic structure theory have been of immense importance in the historical development of chemistry, and continue to play a key role in the modern understanding of molecular electronic structure and reactivity. Such concepts not only allow us to rationalize but also to make predictions for whole classes of new systems. Much of our research work involves the development and applications of modern valence bond approaches to electronic structure – especially the spin-coupled generalized valence bond (SCGVB) approach, which provides a simple highly visual model of the behaviour of correlated electrons in molecules, whilst also producing results of high accuracy. Applications include:

• Studies of organic reaction pathways, typically for electrocyclic reactions. For example, we examined S_N2 identity reactions, addition reactions of singlet dihalocarbenes, aromatic versus diradical character in Cope rearrangements, and hetero-Diels-Alder reactions. More recently we investigated homoaromaticity and polycyclic fused aromatic compounds involving cyclopropenyl rings.

Main collaborator: Peter Karadakov at the University of York. See, especially, here for some nice pictures and explanations.

• Developing and applying new 'auxiliary' tools for analyzing the wavefunctions, electron densities and density matrices from high-level calculations (typically using SCGVB and CASSCF calculations as a testing ground). Most recently we have been using domain-averaged Fermi hole (DAFH) analysis and various multicentre bond indices to understand the bonding in a range of systems, including recently-characterised formally Be(0) complexes.

Main collaborator: Robert Ponec in Prague.

We use various computational strategies, including the CASVB algorithms that have been released for general use via MOLPRO and also via MOLCAS. The most recent version is included in MOLPRO2019.2. CASVB can be used either to perform fully-variational optimization of fairly general types of (multiconfigurational) modern VB wavefunctions or to generate representations of CASSCF wavefunctions in modern VB form, using overlap-based (relatively inexpensive) or energy-based criteria.

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Other research interests

Sizing of gold nanoparticles by differential centrifugal sedimentation

QSAR and momentum-space concepts

Also: Developing new Schools Outreach Activities