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Compound prediction with evolutionary algorithms (MAISE)

Development of bond order potentials

Phonon mediated superconductivity

Superhard materials

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Development of new metal boride superconductors via ab initio modelling
S. Shah, Dr. A.N. Kolmogorov
Development of superconducting materials 'from scratch' involves two critical steps: identification of synthesizable candidates and evaluation of their superconducting properties. Ab initio search for new stable materials is being carried out with advanced evolutionary algorithms. Proposed compounds are then carefully examined for phonon-mediated superconductivity features within the Eliashberg theory. The project's primary goal is to identify promising metal boride materials, a class with exceptionally complex and diverse crystal structures, for future experimental investigation.

Synthesis and characterisation of new materials under high pressures and temperatures
Dr. A.N. Kolmogorov, Professor A.P. Jephcoat*
Materials subjected to extreme conditions can adopt unique crystal structures and exhibit entirely new sets of properties. Synthesis of new materials under high pressure and/or temperature can, for example, provide critical insights into the mechanisms of superconductivity or the nature of bonding in deep-Earth matter. This collaborative project involves a materials science group with primary interest in compound prediction from first principles and a planetary science group with expertise in extreme high P-T methods with the diamond-anvil cell. The goal of the DPhil project is to synthesise and characterise multi-component compounds (metal borides or other light-element systems identified by the predictive modelling work) using these state-of-the-art high-pressure techniques and condensed-matter experiments. The DPhil student will work between the Departments of Materials (base affiliation) and Earth Sciences, and have the opportunity to use laboratory Raman spectroscopic, IR absorption methods, and X-ray diffraction techniques at the UK's 3rd-generation synchrotron at Diamond Light Source.

Simple models for the structural stability of TCP phases
B.J. Seiser, Dr. A.N. Kolmogorov, Dr. T. Hammerschmidt*, Professor R. Drautz*, Professor D.G. Pettifor
The precipitation of topologically close-packed (TCP) phases during the lifetime of a jet engine seriously degrades the mechanical properties of the nickel-based superalloy turbine blades. Atomistic simulations are being performed using a hierarchy of electronic structure models fromfirst principles density functional theory through the more chemically intuitive tight-binding model to analytic bond-order potential theory, in order to investigate the underlying origins of the structural trends between the A15, sigma, chi, mu and Laves TCP phases. Complementary to this theoretical investigation of binary phases, a novel two-dimensional structure map is also being developed that can handle the multi-component systems used in turbine blades. (In collaboration withthe University of Birmingham, Cambridge and Imperial College London.Funded by EPSRC.*ICAMS, Ruhr-Universität Bochum, Germany).

Atomistic modelling of Si-C coatings
P. Kamenski, Dr. A.N. Kolmogorov, Professor R. Drautz*, Professor D.G. Pettifor
Nanocomposite coatings are materials with unique properties that stemfrom a subtle interplay between the nanocrystalline grains and amorphous films, resulting in an overall hardness that exceeds the hardness of the individual components. In this project analytic bond-order potentialsare developed for modelling covalent SiC amorphous films. The robustnessof the interatomic potentials is validated by comparison to both experiment and first-principles density functional calculations. (Incollaboration with Fraunhofer IWM Freiburg and EMPA Dübendorf. Funded byNSF.*ICAMS, Ruhr-Universität Bochum, Germany).

Atomistic modelling of Si-N coatings
J. Gehrmann, Dr. A.N. Kolmogorov, Professor R. Drautz*, Professor D.G. Pettifor
For the modelling of Si-N charge transfer has to be taken into account which requires an extension of the bond-based bond-order potentials for Si-C that are developed in the project "Atomistic modelling of Si-Ccoatings". In this project we include charge transfer into the bond-based BOP formalism. The potentials for Si-N and Si-C are then used in large-scale atomistic simulations of the growth of amorphous thin films. (In collaboration with Fraunhofer IWM Freiburg and EMPADübendorf. Funded by EPSRC.*ICAMS, Ruhr-Universität Bochum, Germany).

5 public active projects

B. Seiser, T. Hammerschmidt, A. N. Kolmogorov, R. Drautz, and D. G. Pettifor: "Theory of structural trends within 4d and 5d transition metal topologically close-packed phases", PHYSICAL REVIEW B 83, Art. No. 224116 2011

A. Bil, B. Kolb, R. Atkinson, D. G. Pettifor, T. Thonhauser, and A. N. Kolmogorov: "van der Waals interactions in the ground state of Mg(BH4)2 from density functional theory", PHYSICAL REVIEW B 83, Art. No. 224103 2011

A. F. Bialon, T. Hammerschmidt, R. Drautz, S. Shah, E. R. Margine, and A. N. Kolmogorov: "Possible routes for synthesis of new boron-rich Fe-B and Fe(1-x)Cr(x)B4 compounds", APPLIED PHYSICS LETTERS 98, Art. No. 081901 2011

A. N. Kolmogorov, S. Shah, E. R. Margine, A. F. Bialon, T. Hammerschmidt, and R. Drautz: "New superconducting and semiconducting Fe-B compounds predicted with an ab initio evolutionary search", PHYSICAL REVIEW LETTERS 105, Art. No. 217003 2010

Y. Chen, A. N. Kolmogorov, D. G. Pettifor, J.-X. Shang, and Y. Zhan: "Theoretical analysis of structural stability of TM5Si3 transition metal silicides",  PHYSICAL REVIEW B 82, Art. No. 184104 2010

Kolmogorov AN, Calandra M, Curtarolo S: 'Thermodynamic stabilities of ternary metal borides: An ab initio guide for synthesizing layered superconductors' PHYSICAL REVIEW B (78): Art. No. 094520 2008

Kolmogorov AN, Drautz R, Pettifor DG: 'Ab initio modeling of Li-B-H boron-chain alloys for hydrogen storage applications' PHYSICAL REVIEW B 76 (18): Art. No. 184102 NOV 2007

Margine ER, Kolmogorov AN, Stojkovic D, Sofo JO, Crespi VH: 'Theory of genus reduction in alkali-induced graphitization of nanoporous carbon' PHYSICAL REVIEW B 76 (11): Art. No. 115436 SEP 2007

Jiang AQ, Awasthi N, Kolmogorov AN, Setyawan W, Borjesson A, Bolton K, Harutyunyan AR, Curtarolo S: 'Theoretical study of the thermal behavior of free and alumina-supported Fe-C nanoparticles' PHYSICAL REVIEW B 75 (20): Art. No. 205426 MAY 2007

Calandra M, Kolmogorov AN, Curtarolo S: 'Search for high T-c in layered structures: The case of LiB' PHYSICAL REVIEW B 75 (14): Art. No. 144506 APR 2007

Kolmogorov AN, Curtarolo S: `Theoretical study of metal borides stability' PHYSICAL REVIEW B 74 (22): Art. No. 224507 DEC 2006

Kolmogorov AN, Curtarolo S: `Prediction of different crystal structure phases in metal borides: A lithium monoboride analog to MgB2' PHYSICAL REVIEW B 73 (18): Art. No. 180501 MAY 2006

Kolmogorov AN, Crespi VH: `Registry-dependent interlayer potential for graphitic systems' PHYSICAL REVIEW B 71 (23): Art. No. 235415 JUN 2005

Kolmogorov AN, Crespi VH, Schleier-Smith MH, et al.: `Nanotube-substrate interactions: Distinguishing carbon nanotubes by the helical angle' PHYSICAL REVIEW LETTERS 92 (8): Art. No. 085503 FEB 27 2004

Chen GG, Bandow S, Margine ER, et al.: `Chemically doped double-walled carbon nanotubes: Cylindrical molecular capacitors' PHYSICAL REVIEW LETTERS 90 (25): Art. No. 257403 JUN 27 2003

Kolmogorov AN, Crespi VH: `Smoothest bearings: Interlayer sliding in multiwalled carbon nanotubes' PHYSICAL REVIEW LETTERS 85 (22): 4727-4730 NOV 27 2000