a very common defect observed during tio deposition, an o ad … · 2020-02-19 · autumn 2013...
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AUTUMN 2013
Newsletter
A very common defect observed during TiO2 deposition, an O ad-atom on therutile surface, above a 5-fold coordinated Ti atom.
(image courtesy of Sabrina Blackwell)
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Newsletter ContentsThis Newsletter... 3
Modelling thin film growth over realistic time scales 4Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4TiO2 thin film growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Metal thin film growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5ZnO thin film growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
High Performance Computing Facilities in the UK 10
Computational Physics Group News 11The Computational Physics Annual PhD Thesis Prize . . . . . . . . . . . . . . . . . . . . . . . . . 11IoP Computational Physics Group - Research Student Conference Fund . . . . . . . . . . . . . . . 11Young Scientist Prize in Computational Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Conference and Workshop reports 12The 40th IOP Annual Spring Conference on Plasma Physics . . . . . . . . . . . . . . . . . . . . . 12UK Monte Carlo User Group Meeting (MCNEG 2013) . . . . . . . . . . . . . . . . . . . . . . . . . 13
Upcoming Events of Interest 14
Computational Physics Group Committee 15
Related Newsletters and Useful Websites 15
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This Newsletter...
Dear Readers,
Following the recent award of the annual IoP Computational Physics Group PhD Prize for thesis submis-sions in 2012, the feature articles for the next two editions of the newsletter will be invited contributionsfrom both our winner, Sabrina Blackwell, and runner-up, James Mithen. Many congratulations to both ofyou and thanks again to all who entered and to our Prize sponsors for their generosity. Further informationcan be found in CPG News together with details of the submission process for the 2013 Prize.
Also in this edition, David Quigley from the IoP CPG committee has written an article on opportunitiesfor accessing High Performance Computing facilities in the UK following recent government investment ine-infrastructure. We would like to include similar articles from other CPG members in future editions ofthe newsletter so if you have any suitable articles that would like to share with the rest of our readershipthen please contact the Editor.
Most URLs in the newsletter have web hyperlinks and clicking on them should take you to the correspond-ing page. Previous editions of the newsletter can be found online at:
www.iop.org/activity/groups/subject/comp/news/page_40572.html
www.soton.ac.uk/∼fangohr/iop_cpg.html
and also in CPG File Archive available via your MyIOP home page.
As always, we value your feedback and suggestions. Enjoy this edition!
David Shipley, Newsletter Editor B [email protected])
(on behalf of the The Computational Physics Group Committee).
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Modelling thin film growth over realistic time scalesS. Blackwell, R. Smith, S. D. Kenny and ∗J. M. WallsDepartment of Mathematical Sciences and ∗Department of Electronic and Electrical EngineeringLoughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
Abstract
Understanding thin film growth is important to many industries such as photovoltaics, semiconductor op-tics, windows and more. Here, photovoltaic technology was the main focus due to the important role itwill play to assist in meeting the energy demands across the world. Thin film growth can be achieved usinga variety of different techniques to deposit a chosen material onto a substrate. Switching between tech-niques leads to a notable difference in the resulting film morphology, quality and properties. In this work,metal and metal oxide thin film growth by industrially scalable physical vapour deposition (PVD) tech-niques was modelled using computer simulation. Evaporation and reactive magnetron sputter depositionare important PVD methods used within industry so the ability to understand the basic mechanisms andto determine which parameters can create specific growth morphology is extremely important. Computersimulation is used here in order to allow a deeper insight into growth mechanisms. Linking simulationwith experiment has enabled the mechanisms of thin film growth and the varying of growth parametersto be understood in much more depth. New long time scale techniques have been developed, allowing thesimulation of systems for up to 10 seconds, much longer than that possible using traditional modellingtechniques. In this work many materials have been modelling; Ag, Al, TiO2 and ZnO. The growth of metalthin films, interesting in many areas of photovoltaics, illustrated how Ag and Al, although similar metals,formed very different surfaces due to one important transition, the Ehrlich-Schwoebel barrier. The TiO2
simulations concluded that in order to produce dense, crystalline films, magnetron sputtering should bethe deposition technique of choice, also highlighting some previously not understood mechanisms. Finally,ZnO was investigated and phase boundaries were found to be prominent in deposited films.
Introduction
Long time scale dynamics requires the implementation of numerous techniques in order to simulate thinfilm growth. The deposition event was simulated using traditional MD. When simulating a system of Natoms using MD, it is necessary to describe the interatomic interactions. Specific potentials were chosenbased on the material investigated; simple pair potentials to complicated bond order and variable chargepotentials were applied. In order to model diffusion and relaxation between depositions, an on-the fly Ki-netic Monte Carlo (otf-KMC) [1] method was used, which allowed the employment of transition searchesat each step of the simulation. The main parts of this method included a relaxation and translation method(RAT) [2], a method developed in-house at Loughborough University, which searches for saddle points on3N dimensional surfaces and the nudged elastic band (NEB) method [3, 4, 5, 6], which then calculatedthe transition energy barriers more accurately. Also required during both the MD and otf-KMC phases, wasan energy minimisation technique, allowing all atoms to relax into minimum energy sites. A conjugategradient minimiser was used. The strength of these methods was the ability to run in parallel, over mul-tiple cores, thus allowing simulations to be performed in a realistic time scale. Figure 1 demonstrates theparallelisation model, where MD simulates the deposition on a single processor, whilst transition searchesand barrier calculating are employed on multiple (n-1) processors. The MD was performed using LBOMD(Loughborough molecular dynamics), a package developed at Loughborough University [7]. Incorporatedin the simulation codes was the ability to initialise transition searches on multiple processors. The filesrequired were copied to each processor where the transition searches were performed and if successful,minimisation and barrier calculation were also performed. If a transition search was unsuccessful then
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the relevant processor began another search, providing that the number of required searches (typically200) had not yet been reached. This parallelisation required the writing and implementing of many Perlscripts in order to ensure all processors carried out the correct tasks. During the project, between 8 and 48processors were used in parallel on Loughborough Universitys high performance computer (a 1,956 core64-bit Intel Xeon cluster supplied by Bull). The exact number of processors used was simulation specificand optimised for maximum efficiency in each case.
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scripts in order to ensure all processors carried out the correct tasks. During the project, between 8 and 48 processors were used in parallel on Loughborough University’s high performance computer (a 1,956 core 64-bit Intel Xeon cluster supplied by Bull). The exact number of processors used was simulation specific and optimised for maximum efficiency in each case.
Figure 1. The parallelisation model used throughout the growth simulations, where one processor simulates a single deposition and n-1 processors run multiple transition searches, saddle relaxing and barrier calculations until the required number of searches has been exceeded. Metal oxides are of great interest in the photovoltaic industry. The rutile TiO2 (110) surface was investigated using single point depositions, high temperature MD and long time scale dynamics. Otf-KMC enabled simulation for up to 9 seconds of real time, totally inaccessible using traditional MD methods. In order to model the TiO2 interactions, a variable charge QEq model modified at Loughborough University was applied, along with simpler Lennard-Jones and repulsive potentials for the gaseous interactions. We were able to conclude that the evaporation deposition process (impact energies ~ 1eV) produced a void filled, incomplete structure, even with the use of a low energy ion-beam assist. This material is of interest for dye-sensitised solar cells where a dye is injected into the voids. Sputter deposition (impact energies 20-40 eV), in an oxygen-rich environment however, produced dense and crystalline film, which is much applicable to anti-reflective coatings where a crystalline structure is required. Mechanisms which enabled crystalline rutile to form were also investigated, highlighting Ti interstitial annealing in the presence of an O rich surface as a highly important rutile growth mechanism which could never have been guessed using traditional Monte Carlo methods. This work was presented at the MRS Spring Conference in 2011 and published in the proceedings [1]. Following the conference, I was invited to publish an article in Journal of Materials Research by the editor [2]. The article included the results of TiO2 grown via the different PVD methods. An article in Journal of Chemical Physics was also published, describing the methods used and TiO2 simulation results [3]. Later on, after more analysis of Titania growth, the work was presented at the IEEE 38th Photovoltaics Specialists Conference in 2012 and proceedings were published [4]. Metal thin films, of interest due to their uses in reflectors in concentrator photovoltaics, electrical conductors in the monolithic interconnect processes and back contacts, were also investigated using otf-KMC. Relevant Ag and Al interactions were modelled using the Embedded Atom Method, a popular choice for close packed metals allowing many-atom effects to be included, whilst gaseous interactions again were modelled using Lennard-Jones and ZBL repulsive potentials. Growth was simulated for around 0.3 seconds of real
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TiO2 thin film growth
Metal oxides are of great interest in the photovoltaic industry. The rutile TiO2 (110) surface was investi-gated using single point depositions, high temperature MD and long time scale dynamics. Otf-KMC enabledsimulation for up to 9 seconds of real time, totally inaccessible using traditional MD methods. In order tomodel the TiO2 interactions, a variable charge QEq model modified at Loughborough University was ap-plied [8, 9], along with simpler Lennard-Jones [10] and repulsive potentials for the gaseous interactions.We were able to conclude that the evaporation deposition process (impact energies 1eV) produced a voidfilled, incomplete structure, even with the use of a low energy ion-beam assist. This material is of interestfor dye-sensitised solar cells where a dye is injected into the voids. Sputter deposition (impact energies20-40 eV), in an oxygen-rich environment, however, produced dense and crystalline film, which is muchapplicable to anti-reflective coatings where a crystalline structure is required. Mechanisms which enabledcrystalline rutile to form were also investigated, highlighting Ti interstitial annealing in the presence ofan O rich surface as a highly important rutile growth mechanism. This mechanisms, illustrated in figure 2could never have been predicted using traditional Monte Carlo or molecular dynamics methods. This workwas presented at the MRS Spring Conference in 2011 and has been published [11, 12, 13, 14].
Metal thin film growth
Metal thin films, of interest due to their uses in reflectors in concentrator photovoltaics, electrical con-ductors in the monolithic interconnect processes and back contacts, were also investigated using otf-KMC.Relevant Ag and Al interactions were modelled using the Embedded Atom Method [15, 16, 17], a popu-lar choice for close packed metals allowing many-atom effects to be included, whilst gaseous interactions
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Figure 2: A Ti interstitial in the 1st layer is drawn out by the presence of an O rich surface (not shownhere), requiring 0.61 eV to take place. The atoms are coloured by height and only Ti is shown.
again were modelled using Lennard-Jones [10] and ZBL [18] repulsive potentials. Growth was simulatedfor around 0.3 seconds of real time. It was found that Ag has the ability to grow smooth surfaces, usingseveral mechanisms including multiple-atom concerted motion, exchange mechanisms, and damage andrepair mechanisms. Ag (111) and (100) surfaces grew dense, complete and crystalline films when sputter-ing was simulated, however, evaporation deposition could produce incomplete layers and stacking faults.The concerted mechanisms by which the stacking faults form were identified, a 5-atom cluster is static onthe surface and acts as a nucleation site for further arriving atoms. If the cluster is pinned in the correctB layer position then the next layer will grow around it with the natural (111) stacking. If, however, thecluster is in the C position then the next layer will contain a stacking fault. Thus, if two adjacent areas ofthe surface contain a cluster, one in the B position and one in the C position, the clusters will eventuallyform a twin boundary where the B and C clusters intersect. Figure 3 illustrates the growth via evapora-tion deposition where a stacking fault has formed due to a cluster pinning in the C position rather thanB, allowing the new layers to grow in the hcp stack. The inclusion of Ar such as in ion-beam assistedevaporation of Ag (111,) aided growth by transferring extra energy to the surface allowing increased dif-fusion and atomic mixing. Al (111) and (100), however, show different patterns. Growth by evaporationdeposition and magnetron sputtering actually produced very similar results. The inclusion of the ion-beamassist on the Al (111) surface actually damaged the film, producing sub-surface Ar clusters where Al atomswere displaced, creating voids throughout the film. Otf-KMC methods enabled the investigation of specificmechanisms allowing film growth and a very important transition enabling the smooth and complete Alfilm growth was found to be the Ehrlich-Schwoebel (ES) barrier [19, 20]. The ES barrier involves an atomdropping off a step edge of an island and this barrier was found to be much smaller for the Al surfaces,therefore allowing the more complete growth from both evaporation and sputtering. This work has beenpublished [21].
ZnO thin film growth
ZnO, an inorganic compound with many uses including transparent conductive oxides, was also investi-gated in its most stable wurtzite phase. The O-terminated (0001̄) polar surface was used as the substratefor otf-KMC growth simulations, where around 1 second of real time was simulated. Initial testing wascarried out comparing two interatomic potentials, the Albe analytical bond-order potential [22] and thevariable charge reactive force field (ReaxFF) model [23]. After many investigations the ReaxFF potentialwas chosen due to its ability of the variable charge part to model the Zn and ZnO pairs better and due tothe more realistic behaviour of O2 dimers striking the surface. Evaporation deposition of a stoichiometricdistribution of deposition species was found to produce the best quality film, however, a phase boundarywas observed where an area of zinc blende forms within the wurtzite. Sputtering resulted in a denser,more complete and crystalline structure due to the higher deposition energy of arriving species, similar to
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time. It was found that Ag has the ability to grow smooth surfaces, using several mechanisms including multiple-atom concerted motion, exchange mechanisms, and damage and repair mechanisms. Ag (111) and (100) surfaces grew dense, complete and crystalline films when sputtering was simulated, however, evaporation deposition could produce incomplete layers and stacking faults. The concerted mechanisms by which the stacking faults form were indentified, a 5-atom cluster is static on the surface and acts as a nucleation site for further arriving atoms. If the cluster is pinned in the correct B layer position then the next layer will grow around it with the natural (111) stacking. If, however, the cluster is in the C position then the next layer will contain a stacking fault. Thus, if two adjacent areas of the surface contain a cluster, one in the B position and one in the C position, the clusters will eventually form a twin boundary where the B and C clusters intersect. Figure 2 illustrates the growth via evaporation deposition where a stacking fault has formed due to a cluster pinning in the C position rather than B, allowing the new layers to grow in the hcp stack. The inclusion of Ar such as in ion-beam assisted evaporation of Ag (111,) aided growth by transferring extra energy to the surface allowing increased diffusion and atomic mixing. Al (111) and (100), however, show different patterns. Growth by evaporation deposition and magnetron sputtering actually produced very similar results. The inclusion of the ion-beam assist on the Al (111) surface actually damaged the film, producing sub-surface Ar clusters where Al atoms were displaced, creating voids throughout the film. Otf-KMC methods enabled the investigation of specific mechanisms allowing film growth and a very important transition enabling the smooth and complete Al film growth was found to be the Ehrlich-Schwoebel (ES) barrier. The ES barrier involves an atom dropping off a step edge of an island and this barrier was found to be much smaller for the Al surfaces, therefore allowing the more complete growth from both evaporation and sputtering. This work was published in Physical Review B [5].
Figure 2. (a) and (b) the bottom (blue) layer of atoms is labelled as the “A” site and the green layer the “B” site. The energy barrier for motion from the position shown in (a) to (b) is 0.40 eV whilst the reverse barrier is 0.26 eV. The growth of Ag (111) for deposition at 1 eV where three complete monolayers have been deposited is shown in (c). The stacking fault is formed by the pinning of the 4 atom cluster shown in (b) by the arrival of another atom which has diffused over the surface. ZnO, an inorganic compound with many uses including transparent conductive oxides, was also investigated in its most stable wurtzite phase. The O-terminated (000 !1) polar surface was used as the substrate for otf-KMC growth simulations, where around 1 second of real time was simulated. Initial testing was carried out comparing two interatomic potentials, the Albe analytical bond-order potential and the variable charge reactive force field (ReaxFF) model. After many investigations the ReaxFF potential was chosen due to its ability of the variable charge part to model the Zn and ZnO pairs better and due to the more realistic behaviour of O2 dimers striking the surface. Evaporation deposition of a stoichiometric distribution of deposition species was found to produce the best quality film, however, a phase boundary was observed where an area of zinc blende forms within the wurtzite. Sputtering resulted in a denser, more complete and crystalline structure due to the higher deposition energy of arriving species, similar to the TiO2 results. Post-annealing at
Figure 3: Images (a) and (b), the bottom (blue) layer of atoms is labelled as the A site and the green layerthe B site. The energy barrier for motion from the position shown in (a) to (b) is 0.40 eV, whilst the reversebarrier is 0.26 eV. The growth of Ag (111) from deposition at 1 eV, where three complete monolayers havebeen deposited is shown in (c). A stacking fault is formed in the new layers by the pinning of the 4 atomcluster shown in (b) by the arrival of another atom which has diffused over the surface.
the TiO2 results. Post-annealing at 770K did not allow complete recrystallisation, resulting in films withstacking faults where monolayers formed in the zinc blende phase. Annealing at 920K, however, in somecases enabled the complete recrystallisation of films back into the wurtzite structure. Although, the higherannealing temperature did not always enable recrystallisation and in some cases both wurtzite and zincblende phases existed in the same layer, resulting in a phase boundary, as illustrated in figure 4. An impor-tant mechanism for the nucleation of ZnO growth was found to be the formation of ZnxOy strings on thesurface, as illustrated in figure 5, which after hundreds of milliseconds of vibration locked in to form thehexagonal wurtzite structure. This work was published in Journal of Physics: Condensed Matter [24].
Top original
1st new
2nd new
3rd new
4th new
Figure 4: The post-annealed, sputter deposited film, where an O rich distribution of deposition specieswas used. The post-annealing treatment involved heating the system to 920K for 10 ns. The first two newlayers are now perfectly crystalline and in the wurtzite phase. The third new layer is O deficient and astacking fault with a phase boundary has formed between the wurtzite and zinc blende phases.
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Figure 5: ZnxOy strings on the ZnO surface vibrate with small energy barriers of around 0.2eV, until newatoms join on and strings overcome a barrier of 0.42 eV to connect. Finally, after hundreds of milliseconds,the hexagonal wurtzite structure forms. Using traditional methods, these complicated transitions could nothave been identified.
Conclusion
Combining MD and otf-KMC in these long time scale dynamics techniques enabled the simulation of sys-tems over very large time scales which were previously totally inaccessible. Key mechanisms occurringduring the growth of metals and metal oxides were investigated, providing a much more precise under-standing of how growth occurs. It was clear from the work that the deposition technique plays a significantrole on the resulting film quality and surface morphology. Through the new methodology we are now ableto provide an insight into the optimum conditions under which complete, crystalline layers can form.
References
[1] G. Henkelman and H. Jónsson. Long time scale kinetic monte carlo simulations without lattice ap-proximation and predefined event table. Journal of Chemical Physics, 115(21):9657–9666, 2001.
[2] L. J. Vernon. Modelling Growth of Rutile TiO2. Ph.D. thesis, Loughborough University, 2010.
[3] G. Henkelman, D. Sheppard, and R. Terrell. Optimization methods for finding minimum energypaths. Journal of Chemical Physics, 128(134106):1–10, 2008.
[4] H. Jónsson, G. Mills, and K. W. Jacobsen. Classical and Quantum Dynamics in Condensed PhaseSimulations, chapter Nudged Elastic Band Method for Finding Minimum Energy Paths of Transitions,pages 385–404. World Scientific, 1998.
[5] G. Henkelman and H. Jónsson. Improved tangent estimate in the nudged elastic band method fornding minimum energy paths and saddle points. Journal of Chemical Physics, 113(22):9978, 2000.
[6] G. Henkelman, B. Uberuaga, and H. Jónsson. A climbing image nudged elastic band method forfinding saddle points and minimum energy paths. Journal of Chemical Physics, 113(22):9901, 2000.
[7] R. Smith, editor. Atomic and ion collisions in solids and at surfaces: theory, simulation and applications.Cambridge University Press, 1997.
[8] A. K. Rappé and W. A. Goddard. Charge equilibration for molecular dynamics simulations. Journalof Physical Chemistry, 95:3358, 1991.
[9] A. Hallil, R. Tetot, F. Berthier, I. Braems, and J. Creuze. Use of a variable-charge interatomic potentialfor atomistic simulations of bulk, oxygen vacancies, and surfaces of rutile TiO2. Physical Review B,73:165406, 2006.
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[10] J. E. Lennard-Jones. On the determination of molecular fields. ii. from the equation of state of agas. In Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical andPhysical Character (1905-1934), volume 106, pages 463–477, 1924.
[11] S. Blackwell, R. Smith, S. D. Kenny, and J. M. Walls. Modeling the sputter deposition of thin filmphotovoltaics using long time scale dynamics techniques. In MRS Proceedings: Symposium G– ComplexOxide Materials for Emerging Energy Technologies, volume 1327, 2011.
[12] S. Blackwell, R. Smith, S. D. Kenny, L. J. Vernon, and J. M. Walls. Modeling evaporation, ion-beamassist, and magnetron sputtering of TiO2 thin films over realistic timescales. Journal of MaterialsResearch, 27(5):799–805, 2012.
[13] C. Scott, S. Blackwell, L. J. Vernon, S. D. Kenny, J. M. Walls, and R. Smith. Atomistic surface erosionand thin film growth modelled over realistic time scales. Journal of Chemical Physics, 135:174706,2011.
[14] S. Blackwell, R. Smith, S. D. Kenny, and J. M. Walls. Atomistic modeling of titania grown using pvdmethods. In IEEE Proceedings: 38th IEEE Photovoltaic Specialists Conference, pages 002306–002310,2012.
[15] G. J. Ackland, G. Tichy, V. Vitek, and M. W. Finnis. Simple n-body potentials for the noble metals andnickel. Philosophical Magazine A, 56:735, 1987.
[16] G. J. Ackland and V. Vitek. Many-body potentials anti atomic-scale relaxations in noble-metal alloys.Physical Review B, 41(15):10324–10333, 1990.
[17] S. M. Foiles, M. I. Baskes, and M. S. Daw. Embedded-atom-methodfunctions for the fcc metals Cu,Ag, Au, Ni, Pd, Pt and their alloys. Physical Review B, 33(12):7983, 1986.
[18] J. F. Ziegler, J. P. Beirsack, and U. Littmark. The stopping and range of ions in solids, volume 1.Pergamon, New York, 1985.
[19] R. L. Schwoebel and E. J. Shipsey. Step motion on crystal surfaces. Journal of Applied Physics,37:3682, 1966.
[20] G. Ehrlich and F. G. Hudda. Atomic view of surface self diffusion: Tungsten on tungsten. Journal ofChemical Physics, 44:1039, 1966.
[21] S. Blackwell, R. Smith, and S. D. Kenny. Modeling evaporation, ion-beam assist, and magnetronsputtering of thin metal films over realistic time scales. Physical Review B, 86:035416–1–12, 2012.
[22] K. Albe, K. Nordlund, and R. S. Averback. Modeling the metal-semiconductor interaction: Analyticalbond-order potential for platinum-carbon. Physical Review B, 65:195124, 2002.
[23] A. C. T. van Duin, S. Dasgupta, F. Lorant, and W. A. Goddard III. ReaxFF: A reactive force field forhydrocarbons. Journal of Physical Chemistry A, 105:9396–9409, 2001.
[24] S. Blackwell, R. Smith, S. D. Kenny, J. M. Walls, and C. F. Sanz-Navarro. Modelling the growth of znothin films by pvd methods and the effects of post-annealing. Journal of Physics: Condensed Matter,25(13):135002, 2013.
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High Performance Computing Facilities in the UKCPG members may not be aware of opportunities to access high performance and high throughput com-puting resources resulting from the government’s 2011/12 investment in e-infrastructure.This investment created 6 regional centres based around consortia of universities. An initial injection ofcapital has established substantial facilities at each of these centres, intended to be accessible by industryand the private sector as well as for university-based research.
• e-Infrastructure South (www.einfrastructuresouth.ac.uk)A partnership of Bristol, Oxford and Southampton Universities with University College London,formed to develop and share e-infrastructure across the South of England. The consortium boastsa traditional HPC cluster as well as a novel architecture system based around GPU computing.
• MidPlus (www.warwick.ac.uk/fac/cross_fac/midplus/midplus_activities)The MidPlus partnership involves the Universities of Warwick, Nottingham and Birmingham andQueen Mary University London. It brings together academic expertise and leading-edge facilities forcomputing capability and capacity, with an aim to facilitate the rapid realisation of modern compu-tational research methods for business and industry. The partnership currently hosts a 3,000 coreHPC cluster located at Warwick and a 1,800 core capacity cluster located at Queen Mary for highthroughput work.
• HPC Midlands (hpc-midlands.ac.uk)HPC Midlands is an initiative to provide supercomputing to research and industry established byLoughborough University and the University of Leicester. The key component is a 3,000 core HPCcluster.
• N8 HPC (n8hpc.org.uk)Based around the N8 Partnership of 8 research intensive universities in the North of England, the N8HPC initiative aims to seed engagement with industry around research using e-infrastructure. Theinitial government investment has established a 5,000+ core high performance computing facility.
• Archie-West (www.archie-west.ac.uk)Located at the University of Strathclyde and in partnership with the Universities of Glasgow, GlasgowCaledonian, West of Scotland and Stirling, the aim of this Centre is to provide High PerformanceComputing capability for Academia, Industry and Enterprise in the West of Scotland. The facilitycomprises almost 3500 cores for distributed parallel computing.
Many of these centres can also offer expertise and training as well as access to regional-level facilities. CPGmembers are encouraged to follow the above links for further information and contact details if interestedin engaging with any of these centres.
The Hartree Centre (www.stfc.ac.uk/hartree) In parallel with these regional centres, the invest-ment also underpinned the creation of the Hartree Centre at the Sci-Tech Daresbury national science andinnovation campus in Cheshire. This national centre hosts Blue Joule, currently the UK’s number one su-percomputer, and the world’s largest dedicated to software development, plus an additional world classcluster of 8,000 processor cores. The centre exists to enable organisations of every type and size to harnessthe power and potential of cutting-edge high performance computing capabilities and to develop new soft-ware for the next generation of supercomputers.
The government have published a short guide to these and other related facilities for the benefit of industryand the public sector. This can be downloaded at from the gov.uk website.
David Quigley, IoP CPG committee.
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Computational Physics Group News
• The Computational Physics Annual PhD Thesis PrizeEach year, the IoP Computational Physics Group awards a Thesis Prize to the author of the PhD thesisthat, in the opinion of the Committee, contributes most strongly to the advancement of computationalphysics.
The winner of the 2012 Thesis Prize was Dr Sabrina Blackwell for her thesis entitled "Modelling thinfilm growth over realistic time scales", carried out at the University of Loughborough.
This year’s runner-up prize was awarded to Dr James Mithen for his thesis entitled "Molecular dy-namics simulations of the equilibrium dynamics of non-ideal plasmas", carried out at the Universityof Oxford.
Thanks to the generosity of the Smith Institute (www.smithinst.org.uk), AMEC (www.amec.com)and AWE (www.awe.co.uk), Dr Blackwell receives £750 and Dr Mithen £500 for their achievements.Applications are now being accepted for the 2013 Thesis Prize. Eligibility and deadline are as follows:
– Applications are encouraged across the entire spectrum of computational physics.
– Entry is open to all students from an institution in the UK or Ireland, whose PhD examinationhas taken place in 2013.
– The submission deadline is 30th April 2014.
Submission format:
– A four page (A4) abstract.
– A one page (A4) citation from the PhD supervisor.
– A one page (A4) confidential report from the external thesis examiner.
Entries (PDF documents preferred) and any questions relating to the Prize should be sent by email,with "IoP CPG Thesis Prize" as the subject header, to Dr Arash Mostofi ( B [email protected]).
• IoP Computational Physics Group - Research Student Conference FundThe Institute of Physics Computational Physics Group is pleased to invite requests for partial financialsupport towards the cost of attending scientific meetings relevant to the Group’s scope of activity.The aim of the scheme is to help stimulate the career development of young scientists working incomputational physics to become future leaders in the field.
Further details on this award can be found at:
www.iop.org/about/grants/research student/page_38808.html
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• Young Scientist Prize in Computational PhysicsApplications are now invited for the Young Scientist Prize in Computational Physics. The purpose ofthe prize is to promote and award excellence and originality in Computational Physics by outstandingyoung researchers. The assessment criteria are as follows:
– Recipients should be the principal performer of original work of outstanding scientific quality inComputational Physics.
– Recipients, in a given year, should on 1st January of that year have a maximum of eight years ofresearch experience (excluding periods of justifiable research inactivity such as parental leave,national service, extended sick leave etc.) following their PhD.
– Previous recipients will not be eligible for another award.
Further details and application procedure are available on the website:
phycomp.technion.ac.il/%7EC20/prizes.html
Conference and Workshop reports
• The 40th IOP Annual Spring Conference on Plasma Physics
25-28 March 2013 : University of York, UK.Website: plasma13.iopconfs.org
The 40th IoP Annual Spring Conference on Plasma Physics held at the new Ron Cooke Hub at theUniversity of York and was attended by over 100 delegates including 49 IoP Members and 46 stu-dents. There was a wide ranging programme with 24 contributed talks, 80 posters and 10 invitedspeakers. The invited talks included the following topics:
– Designing plasmas for ITER with a Be/W wall in JET by Dr Clive Challis (CCFE)
– Virtual metrology in radio-frequency plasmas by Prof Timo Gans (University of York)
– Lobe structures in ELM mitigation by Dr James Harrison (CCFE)
– Ablation physics at NIF by Dr Ed Hill (Imperial College London)
– Advances in Nanoscience with atmospheric pressure plasmas by Dr Davide Mariotti (University ofUlster)
– Particle acceleration at astronomical and laboratory shocks by Dr Brian Reville (University ofOxford)
– Modelling of the tokamak pedestal by Dr Samuli Saarelma (CCFE)
– Shock compression of materials & warm dense matter by Prof Justin Wark (University of Oxford)
– Supersonic jet and shock interactions in the laboratory by Dr John Foster (AWE)
The 41st IoP Annual Spring Conference on Plasma Physics is planned for 14-17 April 2014 at theGrand Connaught Rooms, London. See the website plasma14.iopconfs.org forfurther details.
Report from Nathan Sircombe, IoP Computational Physics Committee, with the kind assistance of SimonVickers, IoP Plasma Physics Committee
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• UK Monte Carlo User Group Meeting (MCNEG 2013)
28-29 May 2013 : Ipswich Campus, Suffolk University, UK.Website: www.mcneg.org.uk/mcneg13.html
UK users of Monte Carlo radiation transport codes met at the University of Suffolk in Ipswich on28-29 May. The group comprises of physicists who use Monte Carlo radiation transport codes inmany varied applications; this year we had representatives from the medical, defence, academia andradiation protection sectors discussing their work.
FLUKA had a good showing. Alfredo Ferrari (CERN), one of the FLUKA developers and a keynotespeaker, described recent developments and progress with hadrontherapy, and Ihsan al-Affan (Swansea)described a comparison between EGS and FLUKA for simulating photon backscatter in the 250 keVto 2 MeV energy range.
The other invited speaker was Zine el-Abedine Chaoui (Setif, Algeria). Zine described the KATRINspectrometer that his team are using to measure the mass of the neutrino from the fine detail of thetritium beta decay spectrum. Zine’s slide of the spectrometer being delivered through the suburbanstreets of Karslruhe was nominated ’Slide of the Meeting’, and deservedly so!
Delivery of the KATRIN spectrometer through the streets of Karslruhe.
A close runner up had to be Ian Adsley’s (Nuvia) images of a submarine that sank in the Barents seawhile under tow in a gale. Nuvia carried out a survey to measure leakage from the reactor.
Medical applications were well represented. David Roberts (Elekta) described the use of BEAMnrcand other codes in linac design and Anthony Carver (Clatterbridge) described backscatter simulationsof the Papillon, a brachytherapy treatment machine for contact irradiation of the rectum. EmilianoSpezi (Cardiff) described cone beam CT dose modelling, which he is introducing into the dose volumehistograms used to clinically evaluate plans.
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Visual Monte Carlo teaching tool developed using MATLAB (Colin Baker and Alan Nahum)
Quantum dot detector simulations were described by Peter Hobson (Brunel University). His teamused the CASINO and PENELOPE codes to look at energy deposition from 60Co sources.
The computational aspects of parallel processing codes were described by Gavin Crowe (AWE). HisMPI engine handles the sharing of particles to ensure that no individual processor has to cold theentire mesh.
Colin Baker (Clatterbridge) described a Monte Carlo teaching tool that he built using MATLAB toteach the principles of radiation transport physics as part of their MSc course.
Richard Hugtenburg (Swansea) discussed simulating protons using FLUKA in order to perform mi-crodosimetry. The detectors he used were gold coated optical fibres.
In the evening we were entertained by "Bill Ceilidh and the Hobbits" and "Blythe Power". The pre-ponderance of male delegates limited the number of dancers, but Jerry’s girlfriend (Blythe Power)made up for these low statistics with her exuberance!
In 2014 we meet at Clatterbridge Cancer Centre in the Wirrall, and all are warmly invited. Furtherdetails can be found on www.mcneg.org.uk
Report from Henry Lawrence, Ipswich Hospital, Chair MCNEG 2013
Upcoming Events of InterestUpcoming events of interest to our readers can now be found via the following web links.
• IOP’s index page for scientific meetings, including conferences, group events and interna-tional workshops:www.iop.org/events/scientific/index.html
• IOP Conferences page for conference information, calendar and noticeboard:www.iop.org/events/scientific/conferences/index.html
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• All events being run or supported by IOP Groups including calendar and links to event webpages:
www.iop.org/events/scientific/group/index.html
• Thomas Young Centre: The London Centre for Theory and Simulation of Materials organisesmany different kinds of scientific events on the theory and simulation of materials, includingHighlight Seminars, Soirees and Workshops. For further details of upcoming events pleasevisit:
www.thomasyoungcentre.org/events/
• CECAM is a European organization devoted to the promotion of fundamental research onadvanced computational methods for atomistic and molecular simulation and their applica-tion to important problems in science and technology. CECAM organises a series of scientificworkshops, tutorials and meetings. For further details please visit:
www.cecam.org
Computational Physics Group CommitteeThe current members of the IoP Computational Physics Group committee with their contact details are asfollows:
Hans Fangohr [email protected] Hazelwood (Chair) [email protected] Hughes [email protected] Hulse [email protected] Mostofi (Thesis prize) [email protected] Pelan [email protected] Pinna [email protected] Quigley [email protected] Richards [email protected] Rogel (Secretary) [email protected] Shipley (Newsletter) [email protected] Sircombe (Treasurer) [email protected]
Some useful web links related to the Computational Physics Group are:
• Group webpagescomp.iop.org
• Newsletterswww.iop.org/activity/groups/subject/comp/news/page_40572.html
www.soton.ac.uk/∼fangohr/iop_cpg.html
Related Newsletters and Useful WebsitesThe Computational Physics Group works together with other UK and overseas computational physicsgroups. We list their newsletter locations and other useful websites here:
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• Newsletter of the Computational Physics Division of the American Physical Society:
www.aps.org/units/dcomp/newsletters/index.cfm
• Europhysicsnews newsletter of the European Physical Society (EPS):
www.europhysicsnews.org/
• Newsletter of the Psi-k (Ψk) network:
www.psi-k.org/newsletters.shtml
• News and articles from the Knowledge Transfer Network for Industrial Mathematics, provid-ing information for industrial and academic collaborators on recent results, milestones andopportunities:
connect.innovateuk.org/web/mathsktn/articles
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