Scalable Quantum Chemistry with Flexible Embedding

We propose to develop and a new piece of software for molecular modelling of reactivity in complex systems, in particular, surface chemistry and heterogeneous catalysis in the presence of solvent such as water.Examples of the science we are targetting are * metal oxide catalysis that work in the presence or water * the binding of pollutant species (heavy metals or toxic organics) to natural minerals in the environment, or specially designed inorganic materials that could potentially remove them from the environment * catalysis by more complex minerals, not well treated by existing treatments but of great industrial importance * design of sensors and photoelectric materials by organic layers on inorganic surfacesWe will do this by combining quantum chemistry (also known as first principles) techniques, which can treat the chemically reacting centres with classical (or empirical) models for the rest of the system (the slab of material which is modelling a surgfae, and the solvent layers on top of it.The novelty in our approach is that we are extending the quality of the interaction between the classically modelled environment and the quantum mechanical calculation in a number of significant respects. We are combining some of our own ideas, such as adapting existing models to include spin polarisation effects with ideas (frozen electron density models for water molecules) that have been developed and tested by others.We are choosing an Open Source quantum chemistry program, NWChem as the basis for the new features because it has been designed from scratch for use on high-performance computers, and is modular in design which will help support the changes we need to make. The MM code (GULP) is already used in our existing work, and works well on parallel machines. Parallel efficiency is a key driver for the design of the interfaced code and will inform the way we implement the new methods.In the long run, it is intended the code developed here will form the nucleus of a modelling framework for a wider range of systems (including biological ones) building on experience we have had in past software projects (www.chemshell.org).

Materials research is an underpinning technology for a wide range of UK industries. In the chemicals industry economic and environmental sustainability of processes depends on innovation in the area of catalysis. The emerging area of supported nanoparticulate catalysts depends on the construction of specific metal/support combinations with the particle size and interface with the oxide playing an important role in catalyst performance. Advances in this field will require fundamental understanding of the connection between catalyst structure and activity for which modelling at the quantum level is an indispensible tool. As such this project will help improve the range of problems that can be addressed by both academic and industrial researchers in this area. For systems of interest, new fundamental insights will be obtained; materials are widely used in industrial context, including electronics, catalysis, energy materials, environmentally friendly materials and materials used as filters and sorbents tackling chemical and or radioactive waste. New classes of minerals will be addressed along with their interfaces with water thus impacting on our knowledge in earth sciences (calcite and water cycles) and biominerals (appatite in tooth enamel and bones etc.) The partners are all active participants in the Collaborative Computational Projects, in particular CCP5 (SCP is chair and CRAC is a past chair). The developments described here are believed to be highly relevant to the use of condensed phase simulation techniques for systems of technological and commercial interest, and it is anticipated that many within the CCP5 network will be able to exploit the software within their own commercial interactions. STFC and UCL have worked together on an earlier embedding scheme for solids and implemented it in ChemShell. This was the main motivations for Accelrys to licence ChemShell as the basis of their QMERA product, which they are now selling commercially. Once the scientific capabilities of the new code have been demonstrated, it should be straightforward to introduce the required additional functionality into the Accelrys QM code, DMol3 so that the new methods can be exploited within Materials Studio (which incorporates GULP already) by a wider, less computationally expert, modelling community.