Imperial College London
Portrait Picture

Nicholas M Harrison

Faculty of Natural Sciences, Department of Chemistry

Chair of Computational Materials Science
 
 
 
//

Contact

 

+44 (0)20 7594 5884nicholas.harrison Website

 
 
//

Location

 

401LMolecular Sciences Research HubWhite City Campus

//

Summary

 

Publications

Publication Type
Year
to

330 results found

Patel M, Mallia G, Liborio L, Harrison NMet al., 2011, A Hybrid Density Functional Study of Water Adsorption on Rutile TiO2(110) for Applications in Solar Hydrogen Production, http://www.nsti.org/procs/Nanotech2011v1/9/W3.183, Nanotech 2011, Publisher: NSTI

Theoretical and experimental methods are adopted in order to gain further understanding of photocatalytic water splitting over the semiconductor TiO2. Periodic density functional theory calculations are used to study the adsorption of water on the rutile TiO2(110) surface. Results of studying the influence of acidic surface species on the energetics of the system are compared with new experimental measurements of the kinetics (using transient absorption spectroscopy) and photocurrent (photoelectrochemical set-up) as a function of pH.

Conference paper

Martinez-Casado R, Mallia G, Usvyat D, Maschio L, Casassa S, Schuetz M, Harrison NMet al., 2011, He-atom scattering from MgO(100): calculating diffraction peak intensities with a semi <i>ab initio</i> potential, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 14750-14757, ISSN: 1463-9076

Journal article

Martinez-Casado R, Mallia G, Harrison NM, 2011, An alternative approach for the calculation of correlation energy in periodic systems: a hybrid MP2(B3LYP) study of the He-MgO(100) interaction, CHEMICAL COMMUNICATIONS, Vol: 47, Pages: 4385-4387, ISSN: 1359-7345

Journal article

De Fusco GC, Montanari B, Harrison NM, 2010, Half-metallicity in the ferrimagnet Nb(TCNE)<sub>2</sub> from first principles, PHYSICAL REVIEW B, Vol: 82, ISSN: 1098-0121

Journal article

Virk N, Montanari B, Harrison NM, 2010, Ab-initio investigation of graphane, Nanotechnology 2010: Advanced Materials, CNTs, Particles, Films and Composites - Technical Proceedings of the 2010 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2010, Vol: 1, Pages: 296-299

First-principles calculations employing the hybrid exchange functional B3LYP are used to determine the structural parameters, electronic structure and associated properties of a graphene sheet, graphane chair and graphane boat confirmations. Graphane is found to have a band gap corresponding to an electronic insulator at room temperature. The relative performance of the B3LYP functional in comparison to calculations employing generalized gradient approximations (PBE) is also assessed. The B3LYP functional finds the band gap to be almost double that predicted by PBE methods. The choice of functional is found to be insignificant in the determination of the structural parameters.

Journal article

Kaur R, Mallia G, Harrison NM, 2010, A hybrid exchange density functional study of CrO<inf>2</inf> as a spin polarised material for spintronics, Nanotechnology 2010: Electronics, Devices, Fabrication, MEMS, Fluidics and Computational - Technical Proceedings of the 2010 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2010, Vol: 2, Pages: 613-616

Hybrid exchange density functional theory calculations have been carried out to investigate the effects of strain due to a distortion of the lattice parameter(s) on the electronic properties of CrO2, a half metallic ferromagnet. The variation in the density of states near the Fermi level for the majority spin states and the bandgap in the minority spin channel are reported. Understanding such variations is vital to study interface properties of heterostructures based on CrO2.

Journal article

Bailey CL, Mukhopadhyay S, Wander A, Searle B, Harrison Net al., 2010, Predictive Modelling of Aluminium Fluoride Surfaces, Functionalized Inorganic Fluorides, Editors: Tressaud, Publisher: Wiley, ISBN: 9780470740507

Book chapter

Bailey CL, Liborio L, Mallia G, Tomic S, Harrison NMet al., 2010, Defect physics of CuGaS<sub>2</sub>, PHYSICAL REVIEW B, Vol: 81, ISSN: 2469-9950

Journal article

Busayaporn W, Torrelles X, Wander A, Tomic S, Ernst A, Montanari B, Harrison NM, Bikondoa O, Joumard I, Zegenhagen J, Cabailh G, Thornton G, Lindsay Ret al., 2010, Geometric structure of TiO<sub>2</sub>(110)(1X1): Confirming experimental conclusions, PHYSICAL REVIEW B, Vol: 81, ISSN: 1098-0121

Journal article

Bailey CL, Liborio L, Mallia G, Tomić S, Harrison NMet al., 2010, Calculating charged defects using CRYSTAL, Journal of Physics: Conference Series, Vol: 242, ISSN: 1742-6588

The methodology for the calculation of charged defects using the CRYSTAL program is discussed. Two example calculations are used to illustrate the methodology: He+ ions in a vacuum and two intrinsic charged defects, Cu vacancies and Ga substitution for Cu, in the chalcopyrite CuGaS2. © 2010 IOP Publishing Ltd.

Journal article

Harrison N, Chang ITH, 2010, Consolidation of elemental aluminium powders using equal channel angular pressing (ECAP)

The aim is to optimise the consolidation of elemental aluminium powder particles by analysing the effect of different powder sizes on apparent density of powders, density of cold compacted samples and density of ECAP samples. Three different sizes (<45μm, 75-105μm, >150μm) of aluminium powders were conventionally compacted at room temperature (400MPa) for comparison and consolidated in a single pass of ECAP at 200°C (400MPa). Grain size distributions show a significant shift to more refined grain sizes following a single pass of ECAP and better bonding of powder particles. The medium and coarse powder particles achieved the highest density but the fine powder particles showed the smallest grain sizes and highest hardness values.

Conference paper

Kaur R, Mallia G, Yates KA, Harrison NMet al., 2010, Computer Simulations of CrO2 as a Spin Polarized Material for Spintronics, http://www.nsti.org/procs/Nanotech2010v2/10/T30.102, Nanotech 2010, Publisher: NSTI, Pages: 613-616

Despite theoretical predictions of chromium dioxide being a half-metallic ferromagnet. Devices based on chromium dioxide have performed poorly. One major issue is the influence of defects on the electronic structure and magnetic properties as well as variations of these properties at surfaces and interfaces. The primary objective of this research is to model point defects in bulk chromium dioxide and at the surface. Here, hybrid density functional theory calculations are used to investigate two point defect candidates: oxygen vacancies and chromium interstitials. The results of this research will be discussed and compared with Yates surface data of chromium dioxide.

Conference paper

Montanari B, Harrison NM, 2010, Spin Dependent Transport in Carbon Nanostructures, http://www.nsti.org/procs/Nanotech2010v1/2/W21.303, Nanotech 2010, Publisher: NSTI, Pages: 211-214

A theoretical investigation of the electronic and magnetic structure in carbon nanoribbons, defective graphene and carbon peapod structures. The critical importance of electron correlation in the emergent behaviour will be demonstrated for; the generation of long range magnetic interactions, spin dependent transport and the localisation of well defined spin qubits.

Conference paper

Chew S, Liborio L, Harrison NM, 2010, An Ab Initio Study of CuGaSe2 (001) Surface, Nanotech 2010, Publisher: NSTI, Pages: 689-692

The chalcopyrite material CuIn1-xGaxSe2 makes one of the best performing devices for thin film solar cells. Despite this, there is still a lack of understanding of some of the fundamental properties of the material. CuGaSe2 based solar cells show only an efficiency of 9.5%, approximately half the efficiency of Cu(In,Ga)Se2 based solar cells. It is important to investigate surface and bulk properties of the material, and its defect states to improve solar cell efficiency. The study will begin by investigating the CuGaSe2 (001) polar surface under a variety of growth conditions by ab initio theoretical studies. Experimental studies on this surface have already been done (Deniozou et al., 2005a, Deniozou et al., 2005b), and LEED characterization of the surface shows clear (4x1) reconstruction without faceting for CuGaSe2 grown under moderate Cu-excess conditions. The sample grown under low Cu-excess conditions exhibits steps/facets, and the sample at higher Cu-excess exhibits weaker reconstruction. Our study will complement the above experimental investigations by identifying the stable surface structures of the CuGaSe2 (001) reconstruction, and analyzing their surface states and resonance. Total energy electronic structure calculations based on the implementation of Density Functional Theory (DFT) in the CRYSTAL code (http://www.crystal.unito.it/) will be used.

Conference paper

Bailey CL, Mukhopadhyay S, Wander A, Searle BG, Carr JM, Harrison NMet al., 2010, Reactivity of the β-AlF<sub>3</sub>(100) surface: defects, fluorine mobility and catalysis of the CCl<sub>2</sub>F<sub>2</sub> dismutation reaction, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 12, Pages: 6124-6134, ISSN: 1463-9076

Journal article

Tomic S, Harrison NM, 2010, Electronic structure of III-V’s semiconductors from B3LYP and PBE0 functionals, 29th International Conference on the Physics of Semiconductors, Publisher: American Institute of Physics, Pages: 65-66

Details of the band gaps within semiconductor materials are of paramount importance to a wide range of technological applications. We present the results of two hybrid exchange, B3LYP and PBE0, approximations to density functional theory for the band gaps of zinc-blend and wurtzite structured III-V materials. Agreement with experimentally derived band gaps at characteristic points in the first Brillouin zone is at least as good as that obtained with correlated calculations, perturbation theories and screened exchange functionals. Using experimental lattice constancies for unite cells we conclude that B3LYP functional provides results on energy gaps that are close to experimental values than with PBE0.

Conference paper

Harrison NM, Virk N, Montanari B, 2010, Ab initio investigation of Graphene Based Systems, http://www.nsti.org/procs/Nanotech2010v1/2/W40.311, Nanotech 2010, Publisher: Nano Science and Technology Institute, Pages: 296-299

First-principles calculations employing the hybrid exchange functional B3LYP are used to determine the structural parameters, electronic structure and associated properties of a graphene sheet, graphane chair and graphane boat confirmations. Graphane is found to have a band gap corresponding to an electronic insulator at room temperature. The relative performance of the B3LYP functional in comparison to calculations employing generalized gradient approximations (PBE) is also assessed. The B3LYP functional finds the band gap to be almost double that predicted by PBE methods. The choice of functional is found to be insignificant in the determination of the structural parameters.

Conference paper

Pisani L, Montanari B, Harrison NM, 2009, Stability of the ferromagnetic state in a mixed <i>sp</i><SUP>2</SUP>-<i>sp</i><SUP>3</SUP> carbon system, PHYSICAL REVIEW B, Vol: 80, ISSN: 1098-0121

Journal article

Warner JH, Ruemmeli MH, Ge L, Gemming T, Montanari B, Harrison NM, Buechner B, Briggs GADet al., 2009, Structural transformations in graphene studied with high spatial and temporal resolution, NATURE NANOTECHNOLOGY, Vol: 4, Pages: 500-504, ISSN: 1748-3387

Journal article

Liborio L, Mallia G, Harrison N, 2009, Electronic structure of the Ti<sub>4</sub>O<sub>7</sub> Magneacuteli phase, PHYSICAL REVIEW B, Vol: 79, ISSN: 1098-0121

Journal article

Ge L, Jefferson JH, Montanari B, Harrison NM, Pettifor DG, Briggs GADet al., 2009, Effects of Doping on Electronic Structure and Correlations in Carbon Peapods, ACS NANO, Vol: 3, Pages: 1069-1076, ISSN: 1936-0851

Journal article

Bailey CL, Mukhopadhyay S, Wander A, Searle BG, Harrison NMet al., 2009, Structure and Stability of α-AlF<sub>3</sub> Surfaces, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 113, Pages: 4976-4983, ISSN: 1932-7447

Journal article

De Fusco GC, Pisani L, Montanari B, Harrison NMet al., 2009, Density functional study of the magnetic coupling in V(TCNE)<sub>2</sub>, PHYSICAL REVIEW B, Vol: 79, ISSN: 1098-0121

Journal article

Makarowicz A, Bailey CL, Weiher N, Kemnitz E, Schroeder SLM, Mukhopadhyay S, Wander A, Searle BG, Harrison NMet al., 2009, Electronic structure of Lewis acid sites on high surface area aluminium fluorides: a combined XPS and <i>ab initio</i> investigation, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 11, Pages: 5664-5673, ISSN: 1463-9076

Journal article

Tomic S, Harrison NM, Jones TS, 2009, Absorption characteristics of intermediate band solar cell, 29th International Conference on Physics of Semiconductors, Publisher: AMER INST PHYSICS, Pages: 499-+, ISSN: 0094-243X

Conference paper

Tomic S, Jones TS, Harrison NM, 2008, Absorption characteristics of a quantum dot array induced intermediate band: Implications for solar cell design, APPLIED PHYSICS LETTERS, Vol: 93, ISSN: 0003-6951

Journal article

Goddard PA, Singleton J, Sengupta P, McDonald RD, Lancaster T, Blundell SJ, Pratt FL, Cox S, Harrison N, Manson JL, Southerland HI, Schlueter JAet al., 2008, Experimentally determining the exchange parameters of quasi-two-dimensional Heisenberg magets, New Journal of Physics, Vol: 10, ISSN: 1367-2630

Though long-range magnetic order cannot occur at temperatures T > 0 in a perfect two-dimensional (2D) Heisenberg magnet, real quasi-2D materials will invariably possess nonzero inter-plane coupling J⊥ driving the system to order at elevated temperatures. This process can be studied using quantum Monte Carlo calculations. However, it is difficult to test the results of these calculations experimentally since for highly anisotropic materials in which the in-plane coupling is comparable with attainable magnetic fields J ⊥ is necessarily very small and inaccessible directly. In addition, because of the large anisotropy, the Néel temperatures are low and difficult to determine from thermodynamic measurements. Here, we present an elegant method of assessing the calculations via two independent experimental probes: pulsed-field magnetization in fields of up to 85 T, and muon-spin rotation. We successfully demonstrate the application of this method for nine metalorganic Cu-based quasi-2D magnets with pyrazine (pyz) bridges. Our results suggest the superexchange efficiency of the [Cu(HF2) (pyz) 2]X family of compounds (where X can be ClO4, BF 4, PF6, SbF6 and AsF6) might be controlled by the tilting of the pyz molecule with respect to the 2D planes. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Journal article

Tomic S, Harrison NM, Jones TS, 2008, Electronic structure of QD arrays: application to intermediate-band solar cells, 7th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD '07), Publisher: SPRINGER, Pages: 313-318, ISSN: 0306-8919

Conference paper

Bailey CL, Wander A, Mukhopadhyay S, Searle BG, Harrison NMet al., 2008, Characterization of Lewis acid sites on the (100) surface of β-AlF<sub>3</sub>:: <i>Ab initio</i> calculations of NH<sub>3</sub> adsorption, JOURNAL OF CHEMICAL PHYSICS, Vol: 128, ISSN: 0021-9606

Journal article

Bailey CL, Mukhopadhyay S, Wander A, Searle BG, Harrison NMet al., 2008, First principles characterisation of aluminium trifluoride catalysts, Journal of Physics: Conference Series, Vol: 117, ISSN: 1742-6588

The recently discovered high surface area AlF3 catalyst is characterised with respect to surface composition and structure using calculations based on density functional theory. Under typical reaction conditions the surfaces are found to expose five fold coordinated Al reaction centres and to preferentially adsorb water. The acidic centres are probed using NH3 adsorption which binds strongly indicating strong Lewis acidity. The predicted temperature probed desorption spectrum has features from competing surfaces and features due to strong intermolecular interactions, which are used to interpret the observed spectrum. © 2008 IOP Publishing Ltd.

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: limit=30&id=00306541&person=true&page=6&respub-action=search.html