CCP9 - Computational Electronic Structure of Condensed Matter

Car-Parrinello Methods

The research of the UK Car-Parrinello community continues to be world leading even though the level of competition is intense. It is remarkable how widely total energy pseudopotential calculations are now applied and much of this activity has arisen as a result of the pioneering work of the UK community. For instance, it is now quite common for half the papers at a surface science conference to report the results of total energy pseudopotential calculations. The UK community has managed to maintain its position despite this level competition through continuous innovation. Examples of some of the recent work of the UK Car-Parrinello community are detailed below. It should also be noted that following an agreement between the UK-Car Parrinello Consortium and Molecular Simulations, the CASTEP code is now freely distributed to all UK academics.

  • Important progress has been made by UKCP groups in the use of first-principles methods to calculate free energies and other thermodynamic properties. Examples are the work of GILLAN's and MADDEN's groups on the first-principles calculation of melting curves, and of ACKLAND's group on crystallographic phase transitions in minerals.
  • The pioneering work of HARRISON and GILLAN's groups on the dynamical simulation of the dissociation of water on the TiO2 (110) surface established this approach as a standard technique for studying surface chemistry. Recent work in HARRISON's group has established the importance of inter-adsorbate interactions in molecular dissociation. Simulations are now being carried out on the much larger systems required to understand interactions at lower coverage. These studies have revealed the crucial role of soft surface vibrational modes in mediating long range interactions between adsorbates.
  • The UKCP work of BIRD's group on the adsorption of H2 and O2 on metal surfaces has also been extremely influential. First principles simulations have been crucial in interpreting data on energy-dependent sticking coefficients for adsorption from the gas phase, and have helped to establish the importance of the 'steering' concept in understanding the data. Recent work has provided a new means for understanding the promoting and poisoning effects of co-adsorbates in H2 dissociation.
  • The technological significance of calculations on gas-metal systems has been reinforced by related work in FINNIS's group on the oxidation reaction CO + O → CO2 on the Pt (111) surface (a process that underlies the operation of automobile catalytic converters), and on the hydrogenation of methyl adsorbed on Ni(111).
  • The tremendous potential for using first-principles simulation to study catalysis has been demonstrated by the pioneering work of PAYNE's group on the sorption and deprotonation of methanol in zeolites (work initiated in collaboration with the Materials Chemistry consortium). Since the first-principles methods work with the infinitely extended crystal, rather than using the cluster approach, the calculations fully account for the structure-specific features of different zeolites. This work has already been important in suggesting mechanisms for zeolite catalysis.
  • The ability to tackle complex internal defects in materials has been demonstrated by the BRISTOWE group in their UKCP work on grain boundaries in TiO2, which has revealed the detailed atomic geometries and electronic structures. This work is a crucial first step in understanding the performance of various semiconductor devices, such as varistors and thermistors, which is strongly affected by grain boundaries.
  • The group of ACKLAND has demonstrated that first-principles simulation has a predictive, as well as descriptive, role in studying high-pressure phase transitions: a new phase of GaAs predicted by the group has now been made in the laboratory. Recently, the group has opened up a major new field to first-principles investigation: liquid crystals. This work has demonstrated the power of the DFT-pseudopotential method in predicting the dynamical and electronic properties of large and complex molecules.

Selection of Highlighted Publications

  1. R. Shah, M. C. Payne, M. H. Lee and J. D. Gale,
    "Understanding the catalytic behaviour of zeolites: first principles study of adsorption of methanol",
    Science, 271, 1395 (1996).
  2. I. Dawson, P. D. Bristowe, M-H. Lee, M. C. Payne, M. D. Segall and J. A. White,
    "A first principles study of a tilt grain boundary in rutile",
    Phys. Rev. B 54, 13727 (1996).
  3. P. J. D. Lindan, N. M. Harrison and M. J. Gillan,
    "Mixed dissociative and molecular adsorption of water on the TiO2 (110) surface",
    Phys. Rev. Lett. 80, 762 (1998).
  4. "CO oxidation on Pt(111): an ab initio density functional theory study",
    A. Alavi, P. Hu, T. Deutch, P. Silvestrelli and J. Hutter,
    Phys. Rev. Lett, 80, 3650, (1998).
  5. "Microscopic mechanism for mechanical polishing of diamond (110)",
    M.R. Jarvis, R. Perez,F.M. van Bouwelen and M.C. Payne,
    Phys.Rev.Lett. 80, 3428 (1998).
  6. G. A. de Wijs, G. Kresse, L. Vocadlo, D. Dobson, D. Alfe M. J. Gillan and G. D. Price,
    " The viscosity of liquid iron at the physical conditions of the Earth's core",
    Nature, 392, 805 (1998).
  7. D. Alfe, M. J. Gillan and G. D. Price,
    'Melting curve of iron at Earth's core pressures from ab initio calculations',
    Nature, (1999).
  8. "First principles calculations of the ideal cleavage energy of bulk niobium (111)/ alpha-alumina(0001) interfaces",
    I. G. Batirev, A. Alavi and M. W. Finnis,
    Phys. Rev. Letters, 82, (1999).