D26 - Integrative Computational Chemistry

The main objective of the Action was to increase the power and scope of computational chemistry for realistic applications thus providing useful tools for the European chemical research community. To fully exploit the potential of the modern computational chemistry requires a broader collaboration across traditional boundaries. Action D26 catalysed this process by supporting the creation of networks between computational chemists from different sectors, or between computational chemists and users of computational chemistry in various areas of application.
Action D26 covered more than 100 nodes. The development of methods and their integration as parts of reliable tools for application in many fields of chemistry, such as spectroscopy, magnetochemistry, thermochemistry, environmental chemistry and astrochemistry, has been undertaken. These methods have been compared and partly integrated into ongoing experimental work or applied to the understanding of pre-existing experimental data.

This Action has designed computational methods for broader use in environmental science, nuclear waste treatment that can be applied to large systems. A description of electronic and nuclear continuum states has been achieved by using B-spline basis sets and new continuum algorithms for solving the time dependent Schrödinger equation. These studies include the complete dynamic description of simple molecules, such as, H2, D2, Li2, as well as the photoionisation of large molecules and clusters. An approach to use localised orbitals in calculations using multireference electronic correlation methods on systems with degenerate or pseudo-degenerate ground and excited electronic states has been applied to treat large quasi degenerate systems. The applicability of hierarchical matrices for linear scaling approaches in quantum chemistry has been investigated and found to be competitive with the commonly used sparse matrix formats. Considerable progress has been made towards the development and implementation of high-accuracy methods for treating electron correlation in systems containing heavy atoms. Within D26, highly accurate calculations of potential energy surfaces, and vibrational and rotational levels of small molecules, important in astrophysics, have been performed. The Action has also contributed to highlight important chemical problems concerning structure, relative stability and reactivity between organic superbases and superacids, cyclopentadienyl-type ligands, and cations. Important progress has been made in describing the electronic and magnetic properties of polyoxometalates.

Action D26 comprised of scientific teams belonging to 21 different countries. The achievements of this Action have been disseminated through Action-organised workshops and Working Group meetings, and the publication of many research articles in peer-reviewed journals.