Dr. Charles Patterson
Associate Professor, Physics
Biography
1982 B.Sc. (Hons.) in Chemistry, University of Bristol.
1982-85 PhD in Chemistry, University of Cambridge.
PhD topic: Reactions at single crystal surfaces.
1986-90 Postdoctoral Fellow, University of Pennsylvania.
Research topics: Electron energy loss spectroscopy and X ray photoelectron spectroscopy.
Ab initio computational studies of surfaces and clusters.
1987 Visiting researcher A.T. and T. Bell Laboratories,
Murray Hill, New Jersey.
Research topic: Low energy ion scattering from NiAl(110).
1990 Postdoctoral Research Fellow, Department of Physics, TCD.
Ab initio computational studies of optical properties of
semiconductor surfaces.
1991-04 Lecturer in Science of Materials, Department of Physics,TCD.
Research Interests: Computational materials science.
1997-11 Director of Computational Physics Degree Course, TCD. 2004-current Senior Lecturer/Associate Professor, Department of Physics, TCD.
Publications and Further Research Outputs
Peer-Reviewed Publications
Cassidy, J.P. and Hofierka, J. and Cunningham, B. and Rawlins, C.M. and Patterson, C.H. and Green, D.G., Many-body theory calculations of positron binding to halogenated hydrocarbons, Physical Review A, 109, (4), 2024
Charles H. Patterson, Molecular Ionization Energies from GW and Hartree-Fock Theory: Polarizability, Screening, and Self-Energy Vertex Corrections, Journal of Chemical Theory and Computing, 2024
Arthur-Baidoo, E. and Danielson, J.R. and Surko, C.M. and Cassidy, J.P. and Gregg, S.K. and Hofierka, J. and Cunningham, B. and Patterson, C.H. and Green, D.G., Positron annihilation and binding in aromatic and other ring molecules, Physical Review A, 109, (6), 2024
Rawlins, C.M., Hofierka, J., Cunningham, B., Patterson, C.H., Green, D.G., Many-Body Theory Calculations of Positron Scattering and Annihilation in H2, N2 and CH4, Physical Review Letters, 130, (26), 2023
Rawlins, C.M. and Hofierka, J. and Cunningham, B. and Patterson, C.H. and Green, D.G., Many-Body Theory Calculations of Positron Scattering and Annihilation in H2, N2, and CH4, Physical Review Letters, 130, (26), 2023
Sahoo, Smruti Ranjan, Patterson, Charles H., Spectroscopic Identification of the Charge Transfer State in Thiophene/Fullerene Heterojunctions: Electroabsorption Spectroscopy from GW/BSE Calculations, The Journal of Physical Chemistry C, 127, (32), 2023, p15928-15942
Hofierka, J. and Cunningham, B. and Rawlins, C.M. and Patterson, C.H. and Green, D.G., Many-body theory of positron binding to polyatomic molecules, Nature, 606, (7915), 2022, p688-693
Chaudhuri, D. and Patterson, C.H., TDDFT versus GW/BSE Methods for Prediction of Light Absorption and Emission in a TADF Emitter, Journal of Physical Chemistry A, 126, (51), 2022, p9627-9643
Sahoo, S.R. and Patterson, C.H., Charge transfer excitons in pi -stacked thiophene oligomers and P3[Alkyl]T crystals: CIS calculations and electroabsorption spectroscopy, Journal of Chemical Physics, 157, (7), 2022
Chaudhuri, D. and Patterson, C.H., Reliable prediction of the singlet-triplet gap in TADF molecules with GW/BSE approach, 2022 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), Turin, Italy, 12th September 2022, 2022, pp85-86
C. H. Patterson, Density fitting in periodic systems: Application to TDHF in diamond and oxides, The Journal of Chemical Physics, 153, (6), 2020, p064107
Charles H. Patterson, Excited states of molecular and crystalline acetylene: application of TDHF and BSE via density fitting methods., Molecular Physics, 2020 Sanibel Symposium, St. Simon's Island, GA, USA, February 2020, edited by Rodney Bartlett , 119, (13), 2020, ppe1792568-
Charles H. Patterson, Soumya Banerjee, John F. McGilp, Erratum: Optical and phonon excitations of modified Pandey chains at the Si(111)"2×1 surface [Phys. Rev. B 84 , 155314 (2011)], Physical Review B, 100, (16), 2019
Charles H. Patterson, Photoabsorption Spectra of Small Na Clusters: TDHF and BSE versus CI and experiment, Physical Review Materials, 3, (4), 2019, p043804-1 - 043804-13
McGilp, John and McGuinness, Cormac and Patterson, Charles, Optics of Surfaces and Interfaces PREFACE, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 255, (4), 2018
P. Kumar and C. H. Patterson, Dielectric anisotropy of the GaP/Si(001) interface from first-principles theory, Physical Review Letters, 118, (23), 2017, p237403-
S. Banerjee, C. H. Patterson and J. F. McGilp, Group V adsorbate structure on vicinal Ge(001) surfaces determined from the optical spectrum, Applied Physics Letters, 110, (23), 2017, p233903-
Mehes, E. and Patterson, C.H., Defects at the Si(001)/a-SiO2 interface: Analysis of structures generated with classical force fields and density functional theory, Physical Review Materials, 1, (4), 2017
C. H. Patterson, S. Banerjee, J. F. McGilp, Reflectance anisotropy spectroscopy of the Si(111)-(5 × 2)Au surface, Physical Review B, 94, (15/16), 2016, p165417 - 9 pages
Banerjee, S., McGilp, J.F., Patterson, C.H., Reflectance anisotropy spectroscopy of clean and Sb covered Ge(001) surfaces and comparison with clean Si(001) surfaces, Physica Status Solidi (B) Basic Research, 252, (1), 2015, p78 - 86
C. H. Patterson, Atomic and electronic structures of Si(111)-(√3x√3)R30-Au and (6x6)-Au surfaces, Journal of Physics Condensed Matter, 27, 2015, p475001-
P. Kumar and C. H. Patterson, Reflectance anisotropy of the anatase TiO2(001)-(4x1) surface, J. Phys. Condens. Matter, 26, (44), 2014, p445006 1-6
C. H. Patterson, Hybrid DFT calculation of 57Fe NMR resonances and orbital order in magnetite , Physical Review B, 90, (7), 2014, p075134 1-11
Jorgji, S, McGilp, JF, Patterson, CH, Reflectance anisotropy spectroscopy of Si(111)-(3 x 1)Li and Ag surfaces, PHYSICAL REVIEW B, 87, (19), 2013
Jorgji, S., McGilp, J.F., Patterson, C.H., Reflectance anisotropy spectroscopy of Si(111)-(3×1)Li and Ag surfaces, Physical Review B - Condensed Matter and Materials Physics, 87, (19), 2013, part. no. 195304
Aurab Chakrabarty and Charles H. Patterson, Transition levels of defects in ZnO: Total energy and Janak's theorem methods , Journal of Chemical Physics, 137, 2012, p054709-1 - 054709-6
Charles H. Patterson, High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: First principles calculations , Journal of Chemical Physics, 137, (9), 2012, p094701-1 - 094701-10
Charles H. Patterson, Validity of the HREELS surface dipole selection rule at semiconductor surfaces: Si(001)-(2x1)H/D, EPL, 98, 2012, p66001-1 - 66001-5
C. H. Patterson, S. Banerjee, J. F. McGilp, Optical and phonon excitations of modified Pandey chains at the Si(111)-2×1 surface, Physical Review B, 84, (15), 2011, p155314-
Chakrabarty, A, Patterson, CH, Defect-trapped electrons and ferromagnetic exchange in ZnO, PHYSICAL REVIEW B, 84, (5), 2011
D. J. Arenas, L. V. Gasparov, Wei Qiu, J. C. Nino, C. H. Patterson and D. B. Tanner , Raman study of phonon modes in bismuth pyrochlores , Physical Review B, 82, (21), 2010, p214302-1 - 214302-8
Charles H. Patterson, Exciton: A Code for Excitations in Materials , Molecular Physics, 108, 2010, p1-
Charles H. Patterson, First Principles Calculation of the Structure and Dielectric Properties of Bi2Ti2O7 , Physical Review B, 82, (15), 2010, p155103-
A. D. Rowan, C. H. Patterson and L.V. Gasparov, Hybrid density functional theory applied to magnetite: Crystal structure, charge order, and phonons , Physical Review B, 79, 2009, p205103-1 - 205103-18
Charles H. Patterson, Small polarons and magnetic anti-phase boundaries in Ca2−xNaxCuO2Cl2 (x=0.06,0.12): origin of striped phases in cuprates, Physical Review B, 77, (9), 2008, p94523-1 - 94523-11
Charles H. Patterson, Electronic Structure and Lattice Vibrations of Ca2CuO2Cl2: a hybrid density functional study, Physical Review B, 77, (11), 2008, p115111-1 - 115111-6
Charles H. Patterson and S. Galamić‐Mulaomerović, Electronic Structure and Vibrational Spectra of Magnetite, AIP Conference Proceedings, International Conference on Computational Methods in Science and Engineering, Corfu, Greece, 25-30 September 2007, edited by George Maroulis, University of Patras Charles H. Patterson and Andrew D. Rowan Theodore E. Simos, University of Peloponnese George Maroulis, University of Patras , 963, (2B), American Institute of Physics, 2007, pp371-374
Charles H. Patterson and S. Galamić-Mulaomerovi, Quasiparticle and Optical Excitations in Solid Ne and Ar: GW and BSE Approximations, AIP Conference Proceedings, International Conference on Computational Methods in Science and Engineering, Corfu, Greece, 25-30 September 2007, edited by Charles H. Patterson and S. Galamić-Mulaomerovi &George Maroulis, University of Patras , 963, (2B), American Institute of Physics, 2007, pp241-244
S. Krishnamurthy, C. McGuinness, L. S. Dorneles, M. Venkatesan, J. M. D. Coey, J. G. Lunney, C. H. Patterson, K. E. Smith, T. Learmonth, P.A. Glans, T. Schmitt, J.-H. Guo, Soft x-ray spectroscopic investigation of ferromagnetic Co-doped ZnO, Journal of Applied Physics, 99, (08M111), 2006, p1 - 3
Charles H. Patterson, Role of defects in ferromagnetism in Zn1-xCoxO: A hybrid density functional study, Physical Review B, 74, (14), 2006, p144432-1 - 144432-13
Charles H. Patterson, Comparison of hybrid density functional, Hartree-Fock, and GW calculations on NiO, International Journal of Quantum Chemistry, 106, (15), 2006, p3383 - 3386
S. Galamic-Mulaomerovic and C.H. Patterson, Ab initio many-body calculation of excitons in solid Ne and Ar, Physical Review B, 72, 2005, p035127-1 - 035127-7
Charles H. Patterson, Charge ordered oxygen ions and bi- and tri-Mn polarons in La0.5Ca0.5MnO3, Molecular Physics, 103, (18), 2005, p2507 - 2512
S. Galamic-Mulaomerovic and C.H. Patterson, Band structures of rare gas solids within the GW approximation, Physical Review B, 71, 2005, p195103-1 - 195103-8
Charles H. Patterson, Competing crystal structures in La0.5Ca0.5MnO3: conventional charge order versus Zener polarons, Physical Review B, 72, 2005, p085125-1 - 085125-5
N.P. Konstantinidis and C.H. Patterson, Spin polaron effective magnetic model for La0.5Ca0.5MnO3, Physical Review B, 70, 2004, p064407-1 - 064407-8
C.H. Patterson and G. Zheng, Spin polaron electronic structure of La0.5Ca0.5MnO3: UHF and CI calculations, 272-276, 2004, pp124 - 126
G. Zheng and C.H. Patterson, Ferromagnetic polarons in La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3, Physical Review B, 67, 2003, p220404-1 - 220404-4
Nicastro, M. and Patterson, C.H., Exchange coupling in (formula presented) and (formula presented) Configuration interaction and the coupling mechanism, Physical Review B - Condensed Matter and Materials Physics, 65, (20), 2002, p1-15
C.H. Patterson, Two approaches to teaching computational physics, Computing in Science and Engineering, 4, (6), 2002, p64 - 68
M. Nicastro and C.H. Patterson, Exchange coupling in CaMnO3 and LaMnO3: Configuration interaction and the coupling mechanism, Physical Review B, 65, 2002, p205111-1 - 205111-15
S. Galamic-Mulaomerovic, C.D. Hogan and C.H. Patterson, Eigenfunctions of the inverse dielectric function and response function of silicon and argon, 188, (4), 2001, pp1291 - 1296
M. Nicastro, S. Galamic-Mulaomerovic and C.H. Patterson, Multipolar contributions to electron self-energies:extreme tight binding model, Journal of Physics: Condensed Matter, 13, 2001, p1215 - 1231
M. Nicastro, M. Kuzmin and C.H. Patterson, Spin and orbital ordering in CaMnO3 and LaMnO3: UHF calculations and the Goodenough model, Computational Materials Science, 17, 2000, p445 - 449
T. Somasundaram, R.M. Lynden-Bell RM, C.H. Patterson, The passage of gases through the liquid water vapour interface: a simulation study, Physical Chemistry Chemical Physics, 1, (1), 1999, p143 - 148
Patterson, C.H., Hogan, C.D., Nicastro, M. , Many-body theory applied to optical properties of silicon surfaces, Computer Physics Communications, Europhysics Conference on Computational Physics, Granada, Spain, September 2-5, 121, 1999, 711-
F. Renzoni, J. F. Donegan, C.H. Patterson, Optical gain and linewidth enhancement factor in bulk GaN, Semiconductor Science and Technology, 14, (6), 1999, p517 - 520
T. Somasundaram, M. in het Panhuis, R.M. Lynden-Bell, C.H. Patterson, A simulation study of the kinetics of passage of CO2 and N2 through the liquid/vapor interface of water, Journal of Chemical Physics, 111, (5), 1999, p2190 - 2199
C.D. Hogan, C.H. Patterson, Reflectance anisotropies of silicon surfaces: analysis of spectra in terms of surface excess susceptibilities, 404, (1-3), 1998, pp586 - 589
C.D. Hogan, C.H. Patterson, Reflectance anisotropy of silicon surfaces: Discrete dipole calculation, Physical Review B, 57, (23), 1998, p14843 - 14849
M. in het Panhuis, C.H. Patterson, R.M. Lynden-Bell, A molecular dynamics study of carbon dioxide in water: diffusion, structure and thermodynamics, Molecular Physics, 94, (6), 1998, p963 - 972
D. Herrendorfer and C.H. Patterson, Dipole waves in semiconductors: The dielectric function and plasma oscillations of silicon, Journal of Physics and Chemistry of Solids, 58, (2), 1997, p207 - 220
C.H. Patterson and D. Herrendorfer, Reflectance anisotropy of the Si(100)1x2-As surface: Discrete dipole calculation, Journal of Vacuum Science and Technology A, 15, (6), 1997, p3036 - 3043
D. Herrendorfer, C.H. Patterson, Reflectivity and reflectance anisotropy of Si(100): A polarisable bond model, Surface Science, 375, (2-3), 1997, p210 - 220
J F McGilp, D Weaire and C H Patterson (eds), Epioptics - Linear and Nonlinear Optical Spectroscopy of Surfaces and Interfaces, Berlin, Springer-Verlag, 1995, 1 - 230pp
The linear optical response in, editor(s)J.F. McGilp, D. Weaire, C.H. Patterson , Epioptics: linear and nonlinear optical spectroscopy of surfaces and interfaces, Berlin, Springer, 1995, pp15 - 38, [R. del Sole, A. Shkrebtii, Guo-Ping J., C.H. Patterson]
C.H. Patterson, Bond polarisabilities at the C(111) 1x1-H surface and their application to 3 wave mixing experiments, Surface Science, 304, (3), 1994, p365 - 374
C.H. Patterson, A novel method for calculating bond-bond interactions of large systems, Chemical Physics Letters, 213, (1-2), 1993, p59 - 64
C. H. Patterson, Bond calculation of optical second harmonic generation at gallium-terminated and arsenic-terminated Si(111) surfaces, Journal of Physics Condensed Matter, 4, 1992, p4017 - 4037
J. D. O'Mahony, C. H. Patterson, J. F. McGilp, F. M. Leibsle, P. Weightman and, C. F. J. Flipse, The Au-induced 5 × 2 reconstruction on Si(111), Surface Science, 277, 1992, pL57 - L62
R.P. Messmer, C.H. Patterson, Long bonds in silicon clusters: a failure of conventional Moller-Plesset perturbation theory, Chemical Physics Letters, 192, (2-3), 1992, p277 - 282
M.M. Lynam, L.V. Interrante, C.H. Patterson, R.P. Messmer, Comparison of isoelectronic aluminium nitrogen and silicon carbon double bonds using valence bond methods, Inorganic Chemistry, 30, (8), 1991, p1918 - 1922
C.H. Patterson, R.P. Messmer, Valence bonds in the main group elements 2: the sulfur oxides, Journal of the American Chemical Society, 112, (11), 1990, p4138 - 4150
C.H. Patterson, R.P. Messmer, Bonding and structures in silicon clusters: a valence bond interpretation, Physical Review B, 42, (12), 1990, p7530 - 7555
C.H. Patterson, T.M. Buck, The binding site of CO on NiAl(110) determined by low energy ion scattering, Surface Science, 218, (2-3), 1989, p431 - 451
C.H. Patterson, J.M. Mundenar, P.Y. Timbrell, A.J. Gellman, R.M. Lambert, Molecular pathways in the cyclotrimerization of acetylene on Pd(111): vibrational spectra of the C4H4 intermediate and its thermal decomposition products, Surface Science, 208, (1-2), 1989, p93 - 112
C. H. Patterson and R. P. Messmer, The role of d functions in Sulfur Oxide molecules, Journal of the American Chemical Society, 111, 1989, p8059 - 8060
C. H. Patterson and R. P. Messmer, Structural compromise of the Arsenic terminated Si(111) surface, Physical Review B, 39, 1989, p1372 - 1374
C.H. Patterson, R.M. Lambert, Molecular pathways in the cyclotrimerization of ethyne on palladium - role of the C4 intermediate, Journal of the American Chemical Society, 110, (20), 1988, p6871 - 6877
I. Kamiya, T.M. Buck, T. Sakuri, C.H. Patterson, Preferential sputtering in dilute Cu-Ni alloys, Nuclear Instruments and Methods in Physics Research B Beam Interactions with Materials and Atoms, 33, (1-4), 1988, p479 - 481
C.H. Patterson, R.M. Lambert, Molecular mechanisms in the cyclotrimerization of acetylene to benzene on palladium(111), Journal of Physical Chemistry, 92, (5), 1988, p1266 - 1270
P.A. Schultz, C.H. Patterson, R.P. Messmer, K-CO on Transition Metals: A Local Ionic Interaction, Journal of Vacuum Science and Technology A Vacuum Surfaces and Films, 5, (4 part 2), 1987, p1061 - 1064
C.H. Patterson, R.M. Lambert, Structure and Properties of the Palladium Sulfur Interface S2 Chemisorption on Pd(111), Surface Science, 187, (2-3), 1987, p339 - 358
Non-Peer-Reviewed Publications
Charles H. Patterson, Debapriya Chaudhuri and Smruti Sahoo, Charge transfer states in molecular and crystalline organics with PV and TADF applications, 2024 Sanibel Symposium, St. Augustine, FL, USA, 25th February to 1st, 2024
Charles H. Patterson, Debapriya Chaudhuri and Smruti Ranjan Sahoo, Charge transfer states and electroabsorption spectroscopy: challenges to theory, 16th International Conference on Organic Electronics, Madrid, Spain, 3rd to 7th July 2023, 2023
Smruti Ranjan sahoo and Charles H. Patterson, Charge Transfer Excitons in pi-stacked Thiophene, New Horizone in Photochemical Water Splitting and heterogeneous Catalysis, Dublin, Ireland, 29th-31st May 2022, 2022
B. Cunningham, J. Hofierka, C.M. Rawlins, A.R. Swann, J.P. Cassidy, S.K. Gregg, C.H. Patterson, and D.G. Green, Many-body theory of low-energy positron interactions with atoms, molecules and condensed matter, 2022
Charles H. Patterson and Dermot G. Green, Exciton: a code for many-body calculations in molecules and materials, Psi-k Conference 2022, Lausanne, Switzerland, 22-25 August 2022, 2022
Emilio Artacho (University of Cambridge) Volker Blum (Duke University) Donal Mackernan (University College Dublin) Charles Patterson, David O'Regan Stefano Sanvito (Trinity College Dublin), CECAM Extended Software Development Workshop: Scaling Electronic Structure Applications, 7-18 January 2019, 2019, Trinity College Dublin
Charles H. Patterson, Density fitting approach to many-body calculations, 24th ETSF Workshop on Electronic Excitations, Jena, Germany, 16 - 20 September 20, edited by Claudia Roedl , 2019
P. Kumar and C. H. Patterson, Dielectric Anisotropy of the GaP/Si(001) Interface, DPG Spring Meeting, Berlin, Germany, 11-16 March 2018, 2018
C. H. Patterson, 'EXCITON code', TCD, 2017, -
John McGilp, Cormac McGuinness, Charles Patterson, 12th International Conference on Optics of Surfaces and Interfaces, 25-30 June 2017, 2017, Trinity College Dublin
C. H. Patterson, S. Banerjee, P. Kumar and J. F. McGilp, Au at the Si(111) surface: silicene and Au nanowires probed by optical spectroscopy, Collaborative Conference on 3D and Materials Research, Songdo Convensia, Incheon, S. Korea, 22nd June 2016, 2016
P. Kumar and C. H. Patterson, Optical characterisation of native point defects in ZnO and TiO2, European materials Research Society Spring Meeting, Lille, France, 11th - 15th May 2015, 2015
C. H. Patterson, Crystal structure, charge and orbital order in magnetite: a new perspective from DFT calculations, Group seminar, Korea Advanced Insitute for Science and Technology , 26th November, 2014
C. H. Patterson, Structure, Charge Order, Phonons and IR Spectra of Magnetite, Visit to Indian Institute of Science, Bangalore, Bangalore, India, March 2014, 2014
C. H. Patterson, Optical Spectroscopy of 1-D Nanostructures at Si(111) Surfaces, Group Seminar, Department of Physics, Yonsei University, Seoul, S. Korea, 25th November , 2014
E. Mehes and C. H. Patterson, Defect levels and optical spectra of the Si(001):a-SiO2 interface, Workshop on dielectrics in microelectronics, Kinsale, Co. Cork, Ireland, 9th - 11th June 2014, 2014
C. H. Patterson, The Irish Transition Year and TYPE, The Gangwon Education International Symposium 2014, Chuncheon, Gangwon, S. Korea, 28th November, 2014, Gangwon-do Provincial Office of Education
C. H. Patterson, S. Banerjee, S. Jorgji, P. Kumar, J. F. McGilp, Optical Anisotropy Calculations on Semiconductor and Oxide Surfaces, 10th International Conference on Optics of Surfaces and Interfaces , Chemnitz, Germany, 8th - 13th September, 2013, Dietrich R. T. Zahn (Technische Universität Chemnitz) Friedhelm Bechstedt (Friedrich Schiller University Jena) Norbert Esser (Leibniz-Institut für Analytische Wissenschaften - ISAS e.V.)
C. H. Patterson and C. McNamee, Transition levels of defects in CuAlo2, DPG Spring Meeting, Regensburg, Germany, 10 - 15 March 2013, 2013
C. H. Patterson, Dielectric properties of semiconductor surfaces, International workshop on computational materials design and engineering, IIT Jodhpur, India, February, 2013, Prof Ambesh Dixit, IIT Jodhpur
C. H. Patterson, Dielectric properties of silicon surfaces, Group Seminar, S. N. Bose National Centre, Kolkata, India, February, 2013
C. H. Patterson, S. Jorgji and J. F. McGilp, Reflectance anisotropy spectroscopyof clean and adsorbate covered Si(111) surfaces: comparison of experiment and hybrid DFT, DPG Spring Meeting, Regensburg, Germany, 10 - 15 March 2013, 2013
C. H. Patterson (chair) and S. Jorgji, 16th Irish Atomistic Simulators Meeting, December 2012, 2012, Trinity College Dublin
C. H. Patterson (chair) and S. Jorgji, 16th Irish Atomistic Simulators Meeting, December 2012, 2012, Trinity College Dublin
S. Banerjee, S. Jorgji, J. F. McGilp and C. H. Patterson,, Reflectance anisotropy spectroscopy of clean and adsorbate-covered Si(111) surfaces: comparison of experiment and hybrid density functional theory, German Physical Society March Meeting Berlin 2012, Berlin, 25-30 March 2012, 2012
A. Chakrabary and C. H. Patterson, F-Centres and Ferromagnetism in Oxides, 75th Annual Meeting of the German Physical Society, Dresden, Germany, 13-18 March 2011, 2011
Charles H. Patterson, Electronic Structure of Striped Phase of Ca1.875Na0.125CuO2Cl2, 75th Annual Meeting of the German Physical Society, Dresden, Gemany, 13th March 2011, 2011
C. H. Patterson (Chair), G. Watson, S. Elliott, M. Nolan, Computer simulation of oxides: dopants, defects and surfaces, 9-11 September 2009, 2009, Trinity College Dublin
C. H. Patterson, Magnetic defects promote ferromagnetism - do Zener polarons rule at 0K?, Seminar, Oak Ridge National Laboratory, TN, USA, May, 2006
C. H. Patterson, Many-body calculations for solids: progress and prospects, Quantum Theory Project Seminar, Department of Physics, University of Florida, October, 2005, Prof. Rodney Bartlett, University of Florida
C. H. Patterson, Electronic, magnetic and crystal structures of La0.5Ca0.5MnO3, EPSRC Metal Oxides Network Meeting, Rutherford Appleton Laboratory, UK, April, 2004, EPSRC Metal Oxides Network
C. H. Patterson, Ab initio studies of manganites: La0.5Ca0.5MnO3, Condensed Matter Theory Group Seminar, Department of Physics, University of Bristol, July, 2003, Prof James Annett
C. H. Patterson, Ab initio many-body calculations for solids: Ne and Ar, Theoretical Chemistry Group Seminar, Department of Chemistry, University of Turin, April , 2003
C. H. Patterson and G. Zheng, Charge, Orbital and Magnetic Ordering in La0.5Ca0.5MnO3,, Condensed Matter and Material Physics (CMMP) conference, Queen's University, Belfast, April 2003, 2003
Charles H. Patterson, Donal MacKernan, 7th Irish Atomistic Simulators' Meeting, 2002, Trinity College Dublin
C. H. Patterson, The computational physics degree at Trinity College Dublin, American Physical Society Division of Computational Physics Annual Meeting, Massachussetts Institute of Technology , July, 2001, American Physical Society Division of Computational Physics
12th European Physical Society Computational Physics Group Summer School on Computing Techniques in Physics, Teaching Computational Physics, 28 Aug-2 Sept 2000, 2000, Trest, Czech Republic
Charles H. Patterson, 4th Irish Atomistic Simulators' Meeting, 1999, Trinity College Dublin
European Physical Society, Applications of Physics to Financial Analysis (APFA1), 15-17 July 1999, 1999, Trinity College Dublin
C. H. Patterson, Discrete dipole calculations of surface optical properties, International school of solid state physics: EPIOPTICS 4, Erice, Sicily, June, 1996
Charles H. Patterson, R.M. Lynden-Bell, 1st Irish Atomistic Simulators' Meeting, 1996, Trinity College Dublin
Research Expertise
Description
Prediction of excited state properties is essential for tailoring environmentally friendly organic materials for new solar cell and light emitting devices. Treatment of organic molecular systems with large unit cells using conventional plane-wave based codes is prohibitively expensive in computer time. I developed a local, Gaussian basis computer code called Exciton aimed at pursuing many-body calculations in molecules and condensed matter. My research is now focused on modelling excited states of organic molecules and polymers with photovoltaic and light emitting applications and especially charge transfer excited states which lead to formations of charge carriers when a charge transfer excited state decays into charged polarons. This has led to 10 peer reviewed publications since 2020 in leading journals and IRC and SFI grants. Journals include Nature, Physical Review Letters (2), Journal of Chemical Theory and Computing, Journal of Physical Chemistry A and C(2), Physical Review A(2) and Journal of Chemical Physics(2). This has been achieved as a result of about 15 years of intensive code development work on the Exciton code begun during a sabbatical year at the Quantum Theory Project at the University of Florida in 2005/6. Acquiring funding for a major code scientific development project in Ireland is extremely difficult and I have done this work without funding support until recently. It remains difficult to find postdoctoral fellows with the necessary many-body theory and code development experience. Exciton now consists of two parts with 30,000 (molecules) and 37,000 (periodic materials) lines of code written and maintained by me. I have collaborated with Dermot Green"s group in Queen"s University Belfast since 2020. He works on anti-matter matter interactions especially positrons electron interactions. He adapted Exciton to include electron-positron interactions and this led to the joint Nature paper in 2022 which was highlighted in the Irish Times in an unsolicited article.Projects
- Title
- Exciton Computer Code
- Summary
- My research consists of developing and applying electronic structure methods to problems in molecular, condensed matter and materials physics. Electronic structure theory is now a relatively mature field and density functional theory codes are available for many applications. More accurate many body methods, based on electron Green's functions, and electron-hole polarization propagators yield the most accurate predictions of excited state properties (Excitons) of molecules and condensed matter. The Exciton code performs self-consistent field Hartree-Fock calculations as well as GW (Green's function) and Bethe-Salpeter Equation calculations. Electronic structure codes divide roughly into those which represent electron wave functions using plane waves and those which use local orbitals. The former are best suited to crystalline materials with limited numbers of atoms per unit cell, the latter have many advantages for molecules, especially large molecules and systems with little or no symmetry. Accurate electronic structure methods such as the GW Green's function method and Bethe-Salpeter Equation polarization propagator method have applications in optical excitations of biomolecules, photovoltaics and photocatalysts for light harvesting and chemical reaction promotion such as artificial photosynthesis. Development of the Exciton code was begun with two graduate students, Drs. Conor Hogan and Svjetlana Galamic-Mulaomerovic, over a decade ago. That first phase of code development was based on a plane wave representation of the Coulomb potential, which is straightforward to code. The original Exciton code resulted in two publications in Physical Review B in 2005. Based on experience gained in developing the first Exciton code, I began developing an entirely new version of the code during a sabbatical year spent at the Quantum Theory Project, University of Florida, hosted by Prof. Rodney Bartlett. The new code employs the Ewald representation of the Coulomb potential for periodic systems. It makes full use of point, layer or space group symmetries in real and reciprocal space as well as time-reversal symmetry in reciprocal space. Symmetry is also used to transform the Gaussian atomic orbital basis into a symmetry adapted basis, which results in block diagonalization of operators, a reduction of running time and increased accuracy of wave functions. The many-body part of the code relies on an approach called Density fitting, which greatly reduces the time required to calculate Coulomb integrals over molecular orbitals. Current applications of the self-consistent Hartree-Fock, GW and BSE modules in the code to moleclues and molecular complexes have been tested using up to 1800 basis functions in the wave function basis and 4500 basis functions in the density fitting basis. Future development of the code will include the capacity to perform GW and Bethe-Salpeter Equation calculations for crystalline systems. Applications where the code would have significant advantages over plane wave codes are metal organic framework (MOF) materials which have open structures. Exciton is developed in C++ and MPI and consists of around 50,000 lines of code. The current Exciton code is also interfaced to the Crystal code which allows it to perform single-particle optical excitations calculations using wave functions and energy band structures from Crystal. This part of Exciton led to 15 publications in the seven year period since 2010. This version of the code produced two publications in 2005.
- Funding Agency
- Higher Education Authority/Enterprise Ireland
- Date From
- January 2000
- Date To
- Current
- Title
- Surface and Interface Optics Calculations
- Summary
- Light can be used as a probe of the electronic properties of matter in situations where conventional light-in/charged particle-out spectroscopies such as photoelectron spectroscopies cannot. The ejected electron in photoelectron spectroscopy cannot be detected if the ambient surrounding the sample is not high vacuum. In contrast, light-in/light-out spectroscopies such as reflectance measurements can be used without a vacuum ambient. The surface and interface optics project is focussed on applying density functional theory (DFT) methods to calculation of optical spectra of surfaces and interfaces of semiconductors and oxides. The work is done in collaboration with experimentalists, notably Prof. John McGilp in the School of Physics. Recent work on the interface between GaP thin films and the underlying Si substrate has been done with Prof. T. Hannappel and Dr. O. Supplie at the Helmholtz-Zentrum, Berlin who are experimentalists working on this prototype system for III-V semiconductor growth on silicon. Reflection of light by a surface depends on the dielectric responses of atoms from the surface layer to many layers below the surface. In order to use visible light as a probe of electrons at surfaces, it is essential to distinguish the reflected signal coming from the layers immediately at the surface from that coming from many more layers near the surface. One way of doing this is to choose systems where the surface is anisotropic in the surface plane while the underlying layers are isotropic. An example of an isotropic surface is where surface atoms form pairs (or dimerize) in chains at (001) surfaces of silicon or III-V semiconductors. If the difference in reflectivity of light is measured in normal incidence with the optical polarization vector aligned parallel or perpendicular to the dimer chains, then the surface contribution to reflectivity arises only from the anisotropic surface. Reflectance anisotropy spectroscopy (RAS) consists of measuring this difference, usually in the photon energy range from 1 to 5 eV. The experimental measurement by itself yields only a fingerprint of the surface. In order to use RAS to obtain information about electronic properties of the surface, experimental data must be compared to results of our calculations using the Crystal and Exciton codes. These calculations show which features in a RAS spectrum arise from transitions between particular surface states. Armed with this analysis, experimentalists may use the RAS technique to diagnose the electronic properties of a surface on which a semiconductor is being grown under non-high vacuum conditions. One recent highlight of this work has been application of the methods that we have developed since 2010 for calculating RAS for surfaces, to the interface between GaP thin films grown on the Si(001) surface by Hannappel and Supplie in Berlin. They measured the dielectric anisotropy of the interface between the thin film and silicon substrate. My PhD student, Pankaj Kumar, calculated the dielectric anisotropy for this interface using Crystal and Exciton and found agreement between theory and experiment only when the silicon substrate was doped so that the interface was semiconducting. Our work showed that the measured interface dielectric anisotropy arises from electrons trapped in interface states localized in several layers of silicon atoms closest to the first P layer in the GaP thin film. It also showed that if the GaP layer was terminated by a Ga/Si interface, the interface dielectric anisotropy spectrum was quite different. Thus a combination of theory and experiment can show whether a buried interface is conducting or semiconducting and whether the GaP layer in contact with the Si substrate is Ga or P. Our work is, as far as we can tell, the first application of DFT to the optical anisotropy of an interface and it has been accepted for publication in Physical Review Letters.
- Funding Agency
- Science Foundation Ireland
- Date From
- October 2009
- Date To
- September 2014
- Title
- Charge and Orbital Order in Magnetite
- Summary
- Many of the most exotic states and properties of matter such as superconductivity, charge and spin order, etc arise in materials with unpaired electron spins on metal ions such as Fe3+ or Cu2+. My work in this area includes first principles hybrid density functional theory (DFT) calculations on manganites, cuprates and magnetite. Magnetite is a ferrimagnet, also known as lodestone, which has an unusual phase transition between a conducting and semiconducting state at 120 K, known as the Verwey transition. The contribution that I and my student, Andrew Rowan, and Prof. Lev Gasparov at the University of North Florida made in this area is in understanding charge order in the above mentioned materials. My most recent work in this area has been on elucidating the charge order in magnetite in the semiconducting phase of magnetite which exists below the Verwey temperature. The transition has puzzled physicists, including many distinguished scientists, since its discovery by Verwey in 1939. The problem is quite simple to explain. Magnetite consists of Fe3+ ions in tetrahedral 'A' sites and an equal proportion of Fe2+ and Fe3+ ions in octahedral 'B' sites. Fe2+ and Fe3+ ions are in d6 and d5 electronic configurations, respectively. This means that half of the ions at 'B' sites contain one minority spin electron, which is responsible for conduction above the Verwey transition temperature and must somehow become immobile below the Verwey temperature. It is this question that has puzzled physicists for 75 years. A complicating factor in determining the cause of the Verwey transition was that the structure of magnetite in the low temperature phase was poorly resolved because if multiple twinning of domains. It was finally resolved by Attfield and coworkers who used x-ray diffraction on a micron sized grain with one dominant domain in 2012 [Nature 481, 173 (2012)]. The unit cell contains 112 ions and has 16 types of Fe 'B' site and 8 types of 'A' site. The low temperature phase shows charge ordering of electrons on Fe 'B' sites, which is associated with the change in electric conductivity and which was dubbed 'trimeron' formation by Attfield and coworkers. Some chains of 3 Fe ions showed on of the conduction electrons being localized on 3 Fe ions. My contribution to this problem was to calculate the NMR (nuclear magnetic resonance) spectra of 'A' and 'B' site Fe ions in the newly discovered structure of magnetite as a function of crystal orientation in an external magnetic field. NMR is a potentially powerful probe of charge order in Fe compounds because 57Fe is a spin " nucleus which will couple to the minority spin electron in d6 Fe2+. Measurement of the NMR resonance frequency as a function of orientation of the magnetite crystal in a magnetic field yields curves which are characteristic of the shape of the d orbital containing this electron. My paper published in Physical Review B in 2014 showed that hybrid DFT calculations using the Crystal code and the crystal structure published by Attfield and coworkers in 2012 could reproduce the variation of NMR frequency with crystal orientation, and therefore that the charge order in our calculations was correct. I concluded that molecular polarons and charge localization in zig-zag chains (Attfield's trimerons) was responsible for the Verwey transition. Hybrid DFT calculation of 57Fe NMR resonances and orbital order in magnetite , C. H. Patterson, Phys. Rev. B 90, 075134 (2014) Hybrid Density Functional Theory Applied to Magnetite: Crystal Structure, Charge Order and Phonons, A. D. Rowan, C. H. Patterson and L. V. Gasparov, Phys. Rev. B 79 205103 (2009)
- Funding Agency
- Science Foundation Ireland
Recognition
Representations
Board or Steering Group Member, Psi-k Network www.Psi-k.org. European Network funded by successive European Commission Human Capital and Mobility and two 5 year European Science Foundation grants.
Board Member, European Physical Society Computational Physics Group. I served a five year term on the EPS-CPG. This entailed attending board meetings in Prague, organising a biennial Summer School on Computing Techniques in Physics and organisation of the International Union of Pure and Applied Physics(IUPAP) Conference on Computational Physics in Granada, Spain in 2000. I chaired the EPS-CPG Summer School in the Czech Republic in 2000.
I have acted as a PhD External Examiner for the Department of Chemistry, University of Cambridge, Tyndall National Laboratory/University College Cork, Department of Physics, University of Calcutta, India, Department of Physics, IIT Jodhpur, India. Oral examinations were conducted for the first two and thesis reports given for the latter two.
Since January 2023 I have reviewed at least one manuscript for the following journals: Journal of the American Chemical Society (IF 14.4), NPJ Computational materials (IF 9.7), Nanoscale (IF 8.3), Physical Review Letters (IF 8.1), Journal of Physics and Chemistry of Solids (IF 4.3), Heliyon (IF 3.4), Physical Review B (IF 3.2), Physical Review Materials (IF 3.1), Journal of Applied Physics (IF 2.3)
I have served two three year terms as an Institute of Physics in Ireland (IOPI) committee member. The first of these terms was in the 1990"s which included a 2 year term as IOPI Treasurer. The second term was from 2017 to 2020 and I was the rep on the Committee from TCD. Roles included attending IOPI committee meetings in Belfast and Dublin, publicising IOP membership to students in TCD and coordinating applications for degree accreditation by the IOP accreditation committee at IOP headquarters in London. The latter is described in more detail in Service to College.
Awards and Honours
Fellow of TCD
Trinity Global Engagement Award
Memberships
American Physical Society
Institute of Physics