Imperial College London

Professor Michael W. Finnis

Faculty of EngineeringDepartment of Materials

Chair in Materials Theory and Simulation
 
 
 
//

Contact

 

+44 (0)20 7594 6812m.finnis Website

 
 
//

Location

 

2.27BRoyal School of MinesSouth Kensington Campus

//

Summary

 

Publications

Publication Type
Year
to

200 results found

Korbmacher D, Glensk A, Duff A, Finnis MW, Grabowski B, Neugebauer Jet al., 2019, Ab initio based method to study structural phase transitions in dynamically unstable crystals, with new insights on the beta to omega transformation in titanium, PHYSICAL REVIEW B, Vol: 100, ISSN: 2469-9950

Journal article

Mellan TA, Duff A, Grabowski B, Finnis MWet al., 2019, Fast anharmonic free energy method with an application to vacancies in ZrC, Physical Review B: Condensed Matter and Materials Physics, Vol: 100, Pages: 024303-1-024303-11, ISSN: 1098-0121

We propose an approach to calculate the anharmonic part of the volumetric-strain and temperature-dependent free energy of a crystal. The method strikes an effective balance between accuracy and computational efficiency, showing a ×10 speedup on comparable free energy approaches at the level of density functional theory, with average errors less than 1 meV/atom. As a demonstration we make predictions on the thermodynamics of substoichiometric ZrCx, including vacancy concentration and heat capacity.

Journal article

Kumar A, Barda H, Klinger L, Finnis MW, Lordi V, Rabkin E, Srolovitz DJet al., 2018, Anomalous diffusion along metal/ceramic interfaces, NATURE COMMUNICATIONS, Vol: 9, ISSN: 2041-1723

Journal article

Mellan TA, Duff AI, Finnis MW, 2018, Spontaneous Frenkel pair formation in zirconium carbide, Physical Review B, Vol: 98, ISSN: 2469-9950

With density functional theory we have performed molecular dynamics simulations of ZrC which displayed spontaneous Frenkel pair formation at a temperature of 3200 K, some 500 K below the melting point. To understand this behaviour, rarely seen in equilibrium simulations, we quenched and examined a set of lattices containing a Frenkel pair. Five metastable structures were found, and their formation energies and electronic properties were studied. Their thermal generation was found to be facilitated by a reduction of between 0.7 and 1.5 eV in formation energy due to thermal expansion of the lattice. With input from a quasi-harmonic description of the defect free energy of formation, an ideal solution model was used to estimate lower bounds on their concentration as a function of temperature and stoichiometry. At 3000 K (0.81 of the melting temperature) their concentration was estimated to be 1.2% per mole in a stoichiometric crystal, and 0.3% per mole in a crystal with 10% per mole of constitutional vacancies. Their contribution to heat capacity, thermal expansion and bulk modulus was estimated.

Journal article

Finnis MW, First principles approach to model electrochemical reactions: Understanding the fundamental mechanisms behind Mg corrosion, Physical Review Letters, ISSN: 0031-9007

Journal article

Surendralal S, Todorova M, Finnis MW, Neugebauer Jet al., 2018, First-principles approach to model electrochemical reactions: understanding the fundamental mechanisms behind Mg corrosion, Physical Review Letters, Vol: 120, ISSN: 0031-9007

Combining concepts of semiconductor physics and corrosion science, we develop a novel approach that allows us to perform ab initio calculations under controlled potentiostat conditions for electrochemical systems. The proposed approach can be straightforwardly applied in standard density functional theory codes. To demonstrate the performance and the opportunities opened by this approach, we study the chemical reactions that take place during initial corrosion at the water-Mg interface under anodic polarization. Based on this insight, we derive an atomistic model that explains the origin of the anodic hydrogen evolution.

Journal article

Hadian R, Grabowski B, Finnis MW, Neugebauer Jet al., 2018, Migration mechanisms of a faceted grain boundary, PHYSICAL REVIEW MATERIALS, Vol: 2, ISSN: 2475-9953

We report molecular dynamics simulations and their analysis for a mixed tilt and twist grain boundary vicinal to the Σ7 symmetric tilt boundary of the type {123} in aluminum. When minimized in energy at 0K, a grain boundary of this type exhibits nanofacets that contain kinks. We observe that at higher temperatures of migration simulations, given extended annealing times, it is energetically favorable for these nanofacets to coalesce into a large terrace-facet structure. Therefore, we initiate the simulations from such a structure and study as a function of applied driving force and temperature how the boundary migrates. We find the migration of a faceted boundary can be described in terms of the flow of steps. The migration is dominated at lower driving force by the collective motion of the steps incorporated in the facet, and at higher driving forces by the step detachment from the terrace-facet junction and propagation of steps across the terraces. The velocity of steps on terraces is faster than their velocity when incorporated in the facet, and very much faster than the velocity of the facet profile itself, which is almost stationary. A simple kinetic Monte Carlo model matches the broad kinematic features revealed by the molecular dynamics. Since the mechanisms seem likely to be very general on kinked grain-boundary planes, the step-flow description is a promising approach to more quantitative modeling of general grain boundaries.

Journal article

Paxton AT, Sutton AP, Finnis MW, 2017, The challenges of hydrogen and metals, Journal: Philosophical Transactions A: Mathematical, Physical and Engineering Sciences, Vol: 375, ISSN: 1471-2962

The Royal Society Scientific Discussion Meeting ‘The challenges of hydrogen and metals’ was held in Carlton House Terrace, London, UK, on 16–18 January 2017. This is the introductory article to the discussion meeting issue which includes contributed papers and seven discussion papers. Here, we introduce the motivation to hold the Meeting and give a brief overview of the contents. We conclude with acknowledgements.This article is part of the themed issue ‘The challenges of hydrogen and metals’.

Journal article

Tautschnig MP, Harrison NM, Finnis MW, 2017, A model for time-dependent grain boundary diffusion of ions and electrons through a film or scale, with an application to alumina, ACTA MATERIALIA, Vol: 132, Pages: 503-516, ISSN: 1359-6454

A model for ionic and electronic grain boundary transport through thin films, scales or membranes with columnar grain structure is introduced. The grain structure is idealized as a lattice of identical hexagonal cells – a honeycomb pattern. Reactions with the environment constitute the boundary conditions and drive the transport between the surfaces. Time-dependent simulations solving the Poisson equation self-consistently with the Nernst-Planck flux equations for the mobile species are performed. In the resulting Poisson-Nernst-Planck system of equations, the electrostatic potential is obtained from the Poisson equation in its integral form by summation. The model is used to interpret alumina membrane oxygen permeation experiments, in which different oxygen gas pressures are applied at opposite membrane surfaces and the resulting flux of oxygen molecules through the membrane is measured. Simulation results involving four mobile species, charged aluminum and oxygen vacancies, electrons, and holes, provide a complete description of the measurements and insight into the microscopic processes underpinning the oxygen permeation of the membrane. Most notably, the hypothesized transition between p-type and n-type ionic conductivity of the alumina grain boundaries as a function of the applied oxygen gas pressure is observed in the simulations. The range of validity of a simple analytic model for the oxygen permeation rate, similar to the Wagner theory of metal oxidation, is quantified by comparison to the numeric simulations. The three-dimensional model we develop here is readily adaptable to problems such as transport in a solid state electrode, or corrosion scale growth.

Journal article

Faber KT, Asefa T, Backhaus-Ricoult M, Brow R, Chan JY, Dillon S, Fahrenholtz WG, Finnis MW, Garay JE, Garcia RE, Gogotsi Y, Haile SM, Halloran J, Hu J, Huang L, Jacobsen SD, Lara-Curzio E, LeBeau J, Lee WE, Levi CG, Levin I, Lewis JA, Lipkin DM, Lu K, Luo J, Maria J-P, Martin LW, Martin S, Messing G, Navrotsky A, Padture NP, Randall C, Rohrer GS, Rosenflanz A, Schaedler TA, Schlom DG, Sehirlioglu A, Stevenson AJ, Tani T, Tikare V, Trolier-McKinstry S, Wang H, Yildiz Bet al., 2017, The role of ceramic and glass science research in meeting societal challenges: Report from an NSF-sponsored workshop., Journal of the American Ceramic Society, Vol: 100, Pages: 1777-1803, ISSN: 0002-7820

Under the sponsorship of the U.S. National Science Foundation, a workshop on emerging research opportunities in ceramic and glass science was held in September 2016. Reported here are proceedings of the workshop. The report details eight challenges identified through workshop discussions: Ceramic processing: Programmable design and assembly; The defect genome: Understanding, characterizing, and predicting defects across time and length scales; Functionalizing defects for unprecedented properties; Ceramic flatlands: Defining structure‐property relations in free‐standing, supported, and confined two‐dimensional ceramics; Ceramics in the extreme: Discovery and design strategies; Ceramics in the extreme: Behavior of multimaterial systems; Understanding and exploiting glasses and melts under extreme conditions; and Rational design of functional glasses guided by predictive modeling. It is anticipated that these challenges, once met, will promote basic understanding and ultimately enable advancements within multiple sectors, including energy, environment, manufacturing, security, and health care.

Journal article

Paxton AT, Sutton AP, Finnis MW, The challenges of hydrogen and metals, The Challenges of Hydrogen and Metals, Publisher: Royal Society, The, ISSN: 1471-2962

Conference paper

Cheah WL, McComb DW, Finnis MW, 2017, Structure and ionic diffusivity in an yttria-stabilised zirconia/strontium titanate multilayer., Acta Materialia, Vol: 129, Pages: 388-397, ISSN: 1359-6454

Enhanced ionic conductivity observed in a heteroepitaxial multilayer of yttria-stabilised zirconia and (YSZ) and strontium titanate (STO) has variously been attributed to lattice dilation or a disordered oxygen sublattice, leading to high interfacial mobility of anions, as compared to those of the constituent bulk oxides. We seek to understand the mechanism of ionic motion in such heterostructures by first simulating the atomic structure assuming coherent interfaces. After investigating possible low-energy interface structures using a genetic algorithm, we perform molecular dynamics simulations on these structures to examine the anionic diffusivity in the system. We find that the extreme biaxial tensile strain in the YSZ layer, as imposed between layers of STO, induces phases that differ from fluorite. The lowest energy structure is an unknown phase, which we refer to as quasi-cubic and whose cation sublattice resembles an extension of the perovskite; this structure does not lead to enhanced ionic conductivity, in contradiction to some reports in the literature.

Journal article

Finnis MW, Structure and ionic diffusivity in an yttria-stabilised zirconia/strontium titanate multilayer, Acta Materialia

Journal article

Heuer AH, Azar MZ, Guhl H, Foulkes M, Gleeson B, Nakagawa T, Ikuhara Y, Finnis MWet al., 2016, The band structure of polycrystalline Al2O3 and its influence on transport phenomena, Journal of the American Ceramic Society, Vol: 99, Pages: 733-747, ISSN: 1551-2916

Journal article

Guhl H, Lee H-S, Tangney P, Foulkes WMC, Heuer AH, Nakagawa T, Ikuhara Y, Finnis MWet al., 2015, Structural and Electronic Properties of Sigma7 Grain Boundaries in alpha-Al2O3, Acta Materialia, Vol: 99, Pages: 16-28, ISSN: 1873-2453

Applying simulated annealing with a classical potential followed by screening of low-energy structures with density functional theory, we examined the atomic and electronic structures of the View the MathML source and View the MathML source symmetric tilt grain boundaries in α-Al2O3. The lowest energy View the MathML source boundary exhibits a pronounced pattern of alternating columns of exclusively four- or fivefold coordinated Al atoms, with a grain boundary energy of 1.84 Jm−2. For the View the MathML source boundary, numerous structures were found with energy just below 2.11 Jm−2. Furthermore, by analysing the full set of candidate structures generated by simulated annealing for the two grain boundaries, we find that the number of fivefold coordinated Al atoms tends to increase with grain boundary energy, which we can also correlate with the behaviour of the electronic density of states. On the other hand, we find no systematic trend with energy that might be expected for other quantities, notably the excess volume of the interface. We compare simulated high-resolution transmission electron microscope (HRTEM) images of the lowest energy calculated structures with experimental images. The disparate structural and electronic features of these two boundaries suggest reasons for their very different oxygen diffusion coefficients that have been observed experimentally.

Journal article

Duff AI, Davey T, Korbmacher D, Glensk A, Grabowski B, Neugebauer J, Finnis MWet al., 2015, Improved method of calculating ab initio high-temperature thermodynamic properties with application to ZrC, Physical review B: Condensed matter and materials physics, Vol: 91, ISSN: 1098-0121

Thermodynamic properties of ZrC are calculated up to the melting point (Tmelt≈3700K), using density functional theory (DFT) to obtain the fully anharmonic vibrational contribution, and including electronic excitations. A significant improvement is found in comparison to results calculated within the quasiharmonic approximation. The calculated thermal expansion is in better agreement with experiment and the heat capacity reproduces rather closely a CALPHAD estimate. The calculations are presented as an application of a development of the upsampled thermodynamic integration using Langevin dynamics (UP-TILD) approach. This development, referred to here as two-stage upsampled thermodynamic integration using Langevin dynamics (TU-TILD), is the inclusion of tailored interatomic potentials to characterize an intermediate reference state of anharmonic vibrations on a two-stage path of thermodynamic integration between the original DFT quasiharmonic free energy and the fully anharmonic DFT free energy. This approach greatly accelerates the convergence of the calculation, giving a factor of improvement in efficiency of ∼50 in the present case compared to the original UP-TILD approach, and it can be applied to a wide range of materials.

Journal article

Duff AI, Finnis MW, Maugis P, Thijsse BJ, Sluiter MHFet al., 2015, MEAMfit: A reference-free modified embedded atom method (RF-MEAM) energy and force-fitting code, Computer Physics Communications, Vol: 196, Pages: 439-445, ISSN: 0010-4655

Ab initio modeling of materials has become routine in recent years, largely due to the success of density functional theory (DFT). However, for many processes in materials, realism is achieved only when millions of atoms are considered. Currently, such large scale simulations are beyond ab initio capabilities so that one has to resort to effective interatomic potentials that well represent ab initio data on smaller scales. Two of the more widely used types of interatomic potentials are embedded atom method (EAM) and modified embedded atom method (MEAM) potentials. Here we present a code that can use ab initio generated energies and forces to obtain representative EAM and reference-free MEAM type effective interatomic potentials. We illustrate the use of this code with ab initio computed thermal excitations in ZrC.

Journal article

Korbmacher D, Glensk A, Grabowski B, Hickel T, Duff A, Finnis MW, Neugebauer Jet al., 2015, Ab initio description of the Ti BCC to ω transition at finite temperatures, Pages: 755-756

Conference paper

Cecchin D, de la Rica R, Bain RES, Finnis MW, Stevens MM, Battaglia Get al., 2014, Plasmonic ELISA for the detection of gp120 at ultralow concentrations with the naked eye, NANOSCALE, Vol: 6, Pages: 9559-9562, ISSN: 2040-3364

Journal article

Rogal J, Divinski SV, Finnis MW, Glensk A, Neugebauer J, Perepezko JH, Schuwalow S, Sluiter MHF, Sundman Bet al., 2014, Perspectives on point defect thermodynamics, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, Vol: 251, Pages: 97-129, ISSN: 0370-1972

Journal article

Gryaznov D, Finnis MW, Evarestov RA, Maier Jet al., 2014, Oxygen vacancy formation energies in Sr-doped complex perovskites: ab initio thermodynamic study, Solid State Ionics, Vol: 254, Pages: 11-16, ISSN: 0167-2738

Journal article

Sarsam J, Finnis MW, Tangney P, 2013, Atomistic force field for alumina fit to density functional theory, JOURNAL OF CHEMICAL PHYSICS, Vol: 139, ISSN: 0021-9606

Journal article

Horton RM, Haslam AJ, Galindo A, Jackson G, Finnis MWet al., 2013, New methods for calculating the free energy of charged defects in solid electrolytes, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 25, ISSN: 0953-8984

Journal article

Heuer AH, Nakagawa T, Azar MZ, Hovis DB, Smialek JL, Gleeson B, Hine NDM, Guhl H, Lee H-S, Tangney P, Foulkes WMC, Finnis MWet al., 2013, On the Growth of Al_2 O_3 Scales, Acta Materialia, Vol: 61, Pages: 6670-6683

Journal article

Mukhopadhyay S, Finnis MW, Harrison NM, 2013, Electronic structures and phonon free energies of LaCoO3 using hybrid-exchange density functional theory, PHYSICAL REVIEW B, Vol: 87, ISSN: 1098-0121

Journal article

Finnis MW, 2012, Concepts for simulating and understanding materials at the atomic scale, MRS BULLETIN, Vol: 37, Pages: 477-484, ISSN: 0883-7694

Journal article

Mottura A, Finnis MW, Reed RC, 2012, On the possibility of rhenium clustering in nickel-based superalloys, ACTA MATERIALIA, Vol: 60, Pages: 2866-2872, ISSN: 1359-6454

Journal article

Chatain D, Kaplan WD, Finnis M, Scheu Cet al., 2012, Preface to the Special Section E-MRS MACAN, JOURNAL OF MATERIALS SCIENCE, Vol: 47, Pages: 1603-1604, ISSN: 0022-2461

Journal article

Cheah WL, Finnis MW, 2012, Structure of multilayer ZrO2/SrTiO3, JOURNAL OF MATERIALS SCIENCE, Vol: 47, Pages: 1631-1640, ISSN: 0022-2461

Journal article

Mason DR, Race CP, Foulkes WMC, Finnis MW, Horsfield AP, Sutton APet al., 2011, Quantum mechanical simulations of electronic stopping in metals, Nucl. Instrum. Meth. Phys. Res. B, Vol: 269, Pages: 1640-1645, ISSN: 0168-583X

Journal article

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-html.jsp Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: respub-action=search.html&id=00461974&limit=30&person=true