Professor David O'Regan
Professor In, Physics
Biography
David is a Professor in Physics at Trinity College Dublin, The University of Dublin. David leads the Quantum Theory of Materials research group at Trinity. He was elected as a Fellow of the College in 2022.
David is also a Principal Investigator at CRANN Institute, with an affiliation to the SFI AMBER Research Centre. David previously completed his PhD at the Cavendish Laboratory, University of Cambridge, after which he carried out post-doctoral research first there, and then at the École Polytechnique Fédérale de Lausanne (EPFL).
David's research is dedicated to finding unexpected, innovative ways to transform the accuracy, efficiency, and applicability of theory and simulation software for understanding the material world using quantum mechanics. David is particularly known for his work on extending and refining the class of methods known as constrained DFT and DFT+U. Some of his recent work centres around developing improved formulations for first-principles calculation of Hubbard parameters, the interpretation of the calculated J parameter as an quantifier of localised static correlation error, and the development of exactified (double-counting free) DFT+U type functionals based on exact conditions such as the flat-plane condition.
David is also known for his work on simulating, from the electrons up, systems that are both spatially complex (e.g., disordered crystals or molecules) and harbour strong interactions that are beyond the predictive capacity of standard techniques. He is involved in the development of linear-scaling density functional theory methods. He is interested in magnetic and multiple-valence properties, generally, and optical, magneto-optical, and photoemission spectroscopies. A particular focus is placed on these properties as exhibited by transition-metal comprising materials, complexes, and heterostructures.
At Trinity, David has recently served as Director of Teaching & Learning (Undergraduate), Physics (3 years); Chair, School of Physics Teaching & Learning Committee; Member, Central Scholarship Committee (current); College Tutor (6 years); Member, School Executive Committee; Member, Trinity Undergraduate Studies Committee; Member, Institutional Academic Integrity Working Group; Member (current), School EDI Committee, Member (current), Theoretical Physics Degree Course Committee. In previous years he has served as School of Physics Examinations Coordinator; Chair, School of Physics Resumption of Teaching Steering Committee; CRANN seminar series Convenor; Coordinator of the School of Physics Summer Undergraduate Research Experience (SURE) programme, and as the Theoretical Physics Degree Coordinator in Physics.
Publications and Further Research Outputs
Peer-Reviewed Publications
Burgess A.C., Linscott E., O'Regan D.D., Tilted-Plane Structure of the Energy of Finite Quantum Systems, Physical Review Letters, 133, (2), 2024
Burgess, Andrew C., O'Regan, David D., Flat plane based double-counting free and parameter free many-body DFT+U, Physical Review B, 110, (20), 2024
Lambert D.S., O'Regan D.D., Evaluation of first-principles Hubbard and Hund corrected DFT for defect formation energies in non-magnetic transition metal oxides, RSC Advances, 14, (52), 2024, p38645 - 38659
MacEnulty L., Giantomassi M., Amadon B., Rignanese G.-M., O'Regan D.D., Facilities and practices for linear response Hubbard parameters U and J in Abinit, Electronic Structure, 6, (3), 2024
Chai, Ziwei, Si, Rutong, Chen, Mingyang, Teobaldi, Gilberto, O;Regan, David D., Liu, Li-Min, Minimum Tracking Linear Response Hubbard and Hund Corrected Density Functional Theory in CP2K, Journal of Chemical Theory and Computation, 20, (20), 2024, p8984-9002
Moore G.C., Horton M.K., Linscott E., Ganose A.M., Siron M., O'Regan D.D., Persson K.A., High-throughput determination of Hubbard U and Hund J values for transition metal oxides via the linear response formalism, Physical Review Materials, 8, (1), 2024
Bhandary S., Poli E., Teobaldi G., O'Regan D.D., Dynamical Screening of Local Spin Moments at Metal-Molecule Interfaces, ACS Nano, 17, (6), 2023, p5974 - 5983
Burgess A.C., Linscott E., O'Regan D.D., DFT+U-type functional derived to explicitly address the flat plane condition, Physical Review B, 107, (12), 2023
Murray, Christopher P., Mamyraimov, Daniyar, Ali, Mugahid, Downing, Clive, Povey, Ian M., McCloskey, David, O'Regan, David D., Donegan, John F., Monolayer Capping Provides Close to Optimal Resistance to Laser Dewetting of Au Films, ACS Applied Electronic Materials, 5, (8), 2023, p4080-4093
Berman S., Zhussupbekova A., Boschker J.E., Schwarzkopf J., O'Regan D.D., Shvets I.V., Zhussupbekov K., Reconciling the theoretical and experimental electronic structure of NbO2, Physical Review B, 108, (15), 2023, p155141-
MacEnulty L., O'Regan D.D., Optimization strategies developed on NiO for Heisenberg exchange coupling calculations using projector augmented wave based first-principles DFT+U+J, Physical Review B, 108, (24), 2023
Halder, Anita, Bhandary, Sumanta, O'Regan, David D., Sanvito, Stefano, Droghetti, Andrea, Theoretical perspective on the modification of the magnetocrystalline anisotropy at molecule-cobalt interfaces, Physical Review Materials, 7, (6), 2023, p064409-
Lambert, D. S., O'Regan, D. D., Use of DFT+U+J with linear response parameters to predict non-magnetic oxide band gaps with hybrid-functional accuracy, Physical Review Research, 5, (1), 2023
Berman S., Zhussupbekova A., Walls B., Walshe K., Bozhko S.I., Ionov A., O'Regan D.D., Shvets I.V., Zhussupbekov K., Unraveling the atomic and electronic structure of nanocrystals on superconducting Nb(110): Impact of the oxygen monolayer, Physical Review B, 107, (16), 2023
Burgess A.C., Linscott E., O'Regan D.D., The convexity condition of density-functional theory, Journal of Chemical Physics, 159, (21), 2023
Zotti L. A., O'Regan D. D., Adhesion of thin metallic layers on Au surfaces, Journal of Physics Condensed Matter, 34, (27), 2022
Alotibi S, Hickey BJ, Teobaldi G, Ali M, Barker J, Poli E, O'Regan DD, Ramasse Q, Burnell G, Patchett J, Ciccarelli C, Alyami M, Moorsom T, Cespedes O., Enhanced Spin-Orbit Coupling in Heavy Metals via Molecular Coupling., ACS Applied Materials & Interfaces, 13, (4), 2021, p5228-5234
Almohammed, Sawsan, K. Orhan, Okan, Daly, Sorcha, O'Regan, David D., Rodriguez, Brian J., Casey, Eoin, Rice, James H., Electric Field Tunability of Photoluminescence from a Hybrid Peptide-Plasmonic Metal Microfabricated Chip, JACS Au, 1, (11), 2021, p1987-1995
Kenan Elibol, Clemens Mangler, David D. O'Regan, Kimmo Mustonen, Dominik Eder, Jannik C. Meyer, Jani Kotakoski, Richard G. Hobbs, Toma Susi, and Bernhard C. Bayer, Single Indium Atoms and Few-Atom Indium Clusters Anchored onto Graphene via Silicon Heteroatoms, ACS Nano, 15, (9), 2021, p14373-14383
Zhussupbekov, Kuanysh, Walshe, Killian, Walls, Brian, Ionov, Andrei, Bozhko, Sergei I., Ksenz, Andrei, Mozhchil, Rais N., Zhussupbekova, Ainur, Fleischer, Karsten, Berman, Samuel, Zhilyaev, Ivan, O'Regan, David D., Shvets, Igor V., Surface Modification and Subsequent Fermi Density Enhancement of Bi(111), The Journal of Physical Chemistry C, 125, (10), 2021, p5549-5558
Almohammed, S., Fularz, A., Zhang, F., Alvarez-Ruiz, D., Bello, F., O'Regan, D.D., Rodriguez, B.J., Rice, J.H., Flexing Piezoelectric Diphenylalanine-Plasmonic Metal Nanocomposites to Increase SERS Signal Strength, ACS Applied Materials and Interfaces, 12, (43), 2020, p48874-48881
Orhan, O.K., O'Regan, D.D., First-principles Hubbard U and Hund's J corrected approximate density functional theory predicts an accurate fundamental gap in rutile and anatase TiO2, Physical Review B, 101, (24), 2020, p245137-
Rangel, T. and Del Ben, M. and Varsano, D. and Antonius, G. and Bruneval, F. and da Jornada, F.H. and van Setten, M.J. and Orhan, O.K. and O'Regan, D.D. and Canning, A. and Ferretti, A. and Marini, A. and Rignanese, G.-M. and Deslippe, J. and Louie, S.G. and Neaton, J.B., Reproducibility in G0W0 calculations for solids, Computer Physics Communications, 255, (107242), 2020
Rangel, T., Del Ben, M., Varsano, D., Antonius, G., Bruneval, F., da Jornada, F.H., van Setten, M.J., Orhan, O.K., O'Regan, D.D., Canning, A., Ferretti, A., Marini, A., Rignanese, G.-M., Deslippe, J., Louie, S.G., Neaton, J.B., Reproducibility in G
MacEnulty, Lórien, O'Regan, David D., Calculation of the Magnetostatic Energy in Spin Density Functional Theory, Journal of Undergraduate Reports in Physics, 30, (1), 2020, p100005
Roychoudhury S, Sanvito S, O'Regan DD., Neutral excitation density-functional theory: an efficient and variational first-principles method for simulating neutral excitations in molecules., Scientific reports, 10, (1), 2020, p8947
Prentice J.C.A., Aarons J., Womack J.C., Allen A.E.A., Andrinopoulos L., Anton L., Bell R.A., Bhandari A., Bramley G.A., Charlton R.J., Clements R.J., Cole D.J., Constantinescu G., Corsetti F., Dubois S.M.-M., Duff K.K.B., Escartin J.M., Greco A., Hill Q., Lee L.P., Linscott E., O'Regan D.D., Phipps M.J.S., Ratcliff L.E., Serrano A.R., Tait E.W., Teobaldi G., Vitale V., Yeung N., Zuehlsdorff T.J., Dziedzic J., Haynes P.D., Hine N.D.M., Mostofi A.A., Payne M.C., Skylaris C.-K., The ONETEP linear-scaling density functional theory program, Journal of Chemical Physics, 152, (17), 2020
Bello, F. and Orhan, O.K. and Abadia, N. and O'Regan, D.D. and Donegan, J.F., Material Characterization and Thermal Performance of Au Alloys in a Thin-Film Plasmonic Waveguide, OSA Technical Digest, CLEO: Applications and Technology 2019,, San Jose, California United States, , 5-10 May, (8749235), 2019, JTu2A.110-
Orhan, O.K., O'Regan, D.D., TDDFT+U: A critical assessment of the Hubbard U correction to exchange-correlation kernels and potentials, Physical Review B, 99, (16), 2019
Orhan, O.K., O'Regan, D.D., Plasmonic performance of Au
Orhan, O.K. and O'Regan, D.D., Plasmonic performance of AuxAgyCu1-x-y alloys from many-body perturbation theory, Journal of Physics Condensed Matter, 31, (31), 2019
Backes C, Campi D, Szydlowska BM, Synnatschke K, Ojala E, Rashvand F, Harvey A, Griffin A, Sofer Z, Marzari N, Coleman JN, O'Regan DD., Equipartition of Energy Defines the Size-Thickness Relationship in Liquid-Exfoliated Nanosheets., ACS Nano, 13, (6), 2019, p7050-7061
Roychoudhury, S. and O'Regan, D.D. and Sanvito, S., Wannier-function-based constrained DFT with nonorthogonality-correcting Pulay forces in application to the reorganization effects in graphene-adsorbed pentacene, Physical Review B, 97, (20), 2018, p085303-
Linscott, E.B., Cole, D.J., Payne, M.C., O'Regan, D.D., Role of spin in the calculation of Hubbard U and Hund's J parameters from first principles, Physical Review B, 98, (23), 2018
Linda A. Zotti, S. Sanvito, and David D. O'Regan, A simple descriptor for energetics at fcc-bcc metal interfaces, Materials & Design, 142, 2018, p158 - 165
Glenn Moynihan, Stefano Sanvito, and David D. O'Regan, Strain-induced Weyl and Dirac states and direct-indirect gap transitions in group-V materials, 2D Materials, 4, (4), 2017, p045018
Emilio Artacho and David D. O'Regan, Quantum mechanics in an evolving Hilbert space, Physical Review B, 95, (11), 2017, p5155
D. D. O'Regan and G. Teobaldi, Optimization of constrained density functional theory, Physical Review B, 94, (3), 2016
David H. P. Turban, Gilberto Teobaldi, David D. O'Regan, and Nicholas D. M. Hine, Supercell convergence of charge-transfer energies in pentacene molecular crystals from constrained DFT, Physical Review B, 93, (16), 2016
Glenn Moynihan, Gilberto Teobaldi, and David D. O'Regan, Inapplicability of exact constraints and a minimal two-parameter generalization to the DFT+$U$ based correction of self-interaction error, Physical Review B, 94, (22), 2016, p220104(R)
Hanlon D, Backes C, Doherty E, Cucinotta CS, Berner NC, Boland C, Lee K, Harvey A, Lynch P, Gholamvand Z, Zhang S, Wang K, Moynihan G, Pokle A, Ramasse QM, McEvoy N, Blau WJ, Wang J, Abellan G, Hauke F, Hirsch A, Sanvito S, O'Regan DD, Duesberg GS, Nicolosi V, Coleman JN, Liquid exfoliation of solvent-stabilized few-layer black phosphorus for applications beyond electronics., Nature communications, 6, 2015, p8563
Weber C., Cole D.J., O'Regan D.D., Payne M.C., Renormalization of myoglobin-ligand binding energetics by quantum many-body effects, Proceedings of the National Academy of Sciences of the United States of America, 111, (16), 2014, p5790 - 5795, p5790-5795
Weber, C., O'Regan, D.D., Hine, N.D.M., Littlewood, P.B., Kotliar, G., Payne, M.C., Importance of many-body effects in the kernel of hemoglobin for ligand binding, Physical Review Letters, 110, (10), 2013
Heiss, M., Fontana, Y., Gustafsson, A., Wüst, G., Magen, C., O'Regan, D.D., Luo, J.W., Ketterer, B., Conesa-Boj, S., Kuhlmann, A.V., Houel, J., Russo-Averchi, E., Morante, J.R., Cantoni, M., Marzari, N., Arbiol, J., Zunger, A., Warburton, R.J., Fontcuberta I Morral, A., Self-assembled quantum dots in a nanowire system for quantum photonics, Nature Materials, 12, (5), 2013, p439-444
O'Regan, D.D., Hine, N.D.M., Payne, M.C., Mostofi, A.A., Linear-scaling DFT+U with full local orbital optimization, Physical Review B - Condensed Matter and Materials Physics, 85, (8), 2012
O'Regan, David D., Optimised Projections for the Ab Initio Simulation of Large and Strongly Correlated Systems, Springer Berlin Heidelberg, 2012
Weber, C., O'Regan, D.D., Hine, N.D.M., Payne, M.C., Kotliar, G., Littlewood, P.B., Vanadium dioxide: A Peierls-Mott insulator stable against disorder, Physical Review Letters, 108, (25), 2012
Cole, D.J., O'Regan, D.D., Payne, M.C., Ligand discrimination in myoglobin from linear-scaling DFT+ U, Journal of Physical Chemistry Letters, 3, (11), 2012, p1448-1452
O'Regan, D.D., Payne, M.C., Mostofi, A.A., Generalized Wannier functions: A comparison of molecular electric dipole polarizabilities, Physical Review B - Condensed Matter and Materials Physics, 85, (19), 2012
O'Regan, D.D., Payne, M.C., Mostofi, A.A., Subspace representations in ab initio methods for strongly correlated systems, Physical Review B - Condensed Matter and Materials Physics, 83, (24), 2011
O'Regan, D.D., Hine, N.D.M., Payne, M.C., Mostofi, A.A., Projector self-consistent DFT+U using nonorthogonal generalized Wannier functions, Physical Review B - Condensed Matter and Materials Physics, 82, (8), 2010
Non-Peer-Reviewed Publications
A. Cabero del Hierro, K. Zhussupbekov, S. Berman, D. Spurling, A. Zhussupbekova, D. D. O'Regan, I. V. Shvets, and V. Nicolosi, Self-assembled Moiré superstructure of MXene", DPG Spring Meeting of the Condensed Matter Section 2024, Berlin, Germany, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, Error Correction Methods for Local & Semi-Local DFT, International HPC Summer SchooL 2024, Kobe, Japan, 2024
S. Bhandary, E. Poli, G. Teobaldi, and D. D. O'Regan, Dynamical screening of the local spin moments at metal-molecule spintronic interfaces, ACS Spring 2024 National Meeting and Exposition, New Orleans, USA, 2024
D. D. O'Regan, The DFT+U method for strongly-correlated and mixed-valence systems, ONETEP Masterclass 2024, Rutherford Appleton Laboratory, UK, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, Towards exactified DFT+U total energies via the flat plane condition: the BLOR functional, ACS Spring 2024 National Meeting and Exposition, New Orleans, USA, 2024
D. S. Lambert and D. D. O'Regan, First-principles DFT+U+J approach to metal oxide simulation: TiO2, ZrO2, HfO2, Cu2O and ZnO, ACS Spring 2024 National Meeting and Exposition, New Orleans, USA, 2024
L. MacEnulty and D. D. O'Regan, Assessing total energy differences from first-principles DFT+U+J using Heisenberg model mappings of NiO, ACS Fall Meeting 2024, Denver, USA, 2024
L. MacEnulty, J.P.A. de Mendonça, R. Poloni, and D. D. O'Regan, Breakdown and potential remedies for DFT+U total energy differences and linear-response parameter calculations in spin-crossover complexes, ACS Fall Meeting 2024, Denver, USA, 2024
D. S. Lambert and D. D. O'Regan, Accurate modelling of oxide bandgaps and defect levels using first principles DFT+U+J, AMBER Conference 2024, Dublin, 2024
K. Zhussupbekov, A. Cabero del Hierro, S. Berman, D. Spurling, A. Zhussupbekova, D. O'Regan, I. Shvets, and V. Nicolosi, Self-assembled Moiré superstructure of MXene, MRS Spring Meeting and Exhibit, Seattle, USA, 2024
L. MacEnulty and D. D. O'Regan, Assessing the reliability and comparability of first-principles DFT+U total-energies via Heisenberg parameters for NiO, ACS Spring 2024 National Meeting and Exposition, New Orleans, USA, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, A first-principles DFT+U functional for the flat-plane condition robust against stringent test cases, American Physical Society March Meeting, Minneapolis, USA, 2024
D. D. O'Regan, Towards cost-effective correction of self-interaction and static correlation error on subspaces, Burke Theory Group meeting talk, Online, hosted by UC Irvine, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, Tilted Plane Condition on the Energy of Finite Fermionic Systems, Progress in Ensemble Density Functional Theory: Opportunities and Challenges, Durham, UK, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, Exact double counting correction schemes from the flat plane condition, American Physical Society March Meeting, Minneapolis, USA, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, In situ correction of self-interaction & static correlation errors, 20th International Conference on Density Functional Theory and its Applications (DFT 2024), Paris, France, 2024
L. MacEnulty, J.P.A. de Mendonça, R. Poloni, and D. D. O'Regan, Breakdown and potential remedies for DFT+U total energy differences and linear-response parameter calculations in spin-crossover complexes, ACS Fall Meeting 2024, Denver, USA, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, The Tilted Plane Condition, 20th International Conference on Density Functional Theory and its Applications (DFT 2024), Paris, France, 2024
A. C. Burgess, E. Linscott, and D. D. O'Regan, A DFT+U-type functional to correct both self interaction error and static correlation error, 17th International Congress of Quantum Chemistry, Bratislava, Slovakia, 2023
L. MacEnulty (Speaker) and D. D. O'Regan, Navigating the interference of Hubbard Corrections and magnetic model mappings in Approximate DFT, Seminar, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK, 2023
A. Droghetti (Speaker), A. Halder, S. Bhandary, D. D. O'Regan, S. Sanvito, M. M. Radonjic, I. Rungger, L. Chioncel, Exploring magnetic properties and electron correlation effects at hybrid interfaces, CMD30 FisMat 2023, Milan, Italy, 2023
A. Halder, S. Bhandary, D. D. O'Regan, S. Sanvito, A. Droghetti, Modification of the magnetocrystalline anisotropy at molecule-cobalt interfaces (Awarded Best Poster), Joint European Magnetic Symposia 2023, Madrid, Spain, 2023
A. C. Burgess, E. Linscott, and D. D. O'Regan, Capturing static correlation using a new DFT+U-type functional, 3rd Quantum International Frontiers, Lódz, Poland, 2023
D. D. O'Regan, DFT+U+J and constrained DFT in ONETEP, ONETEP Masterclass 2023, Rutherford Appleton Laboratory, UK, 2023
L. MacEnulty (Speaker) and D. D. O'Regan, Assessing total energy differences from first principles DFT+U+J using magnetic orderings in NiO, Seminar, Science et ingénierie des matériaux et des procédés (SimAP), Université Grenoble Alpes, Grenoble, France, 2023
K. Elibol (Speaker), C. Mangler, D. D. O'Regan, K. Mustonen, D. Eder, J. C. Meyer, J. Kotakoski, R. G. Hobbs, T. Susi, B. C. Bayer, and P. A. van Aken, Electron beam fabrication of metal clusters on graphene: From Atomic to Nanoscale Integration, 20th International Microscopy Conference, Busan, Korea, 2023
L. MacEnulty and D. D. O'Regan, Assessment of first-principles DFT+U+J for NiO: PAW projector dependence and Heisenberg model mappings, Psi-k Conference 2022, Lausanne, Switzerland, 2022
S. Berman, K. Zhussupbekov, A. Zhussupbekova, B. Walls, K. Walshe, S. I. Bozhko, A. Ionov, D. D. O'Regan, and I. V. Shvets, Structure of NbO Nanocrystals on the Nb(110) Surface, DPG Meeting of the Condensed Matter Section 2022, Regensburg, Germany, 2022
D. D. O'Regan, First-Principles Hund's J: a Promising yet Intriguing Low-Cost Generalised Kohn-Sham Band-Gap Correction Device, 19th International Conference on Density Functional Theory and its Applications (DFT 2022), Brussels, Belgium, 30th August 2022, 2022
L. MacEnulty and D. D. O'Regan, Projectors and Hubbard Parameters and Abinit: Projectors and Hubbard Parameters and Abinit, Rignanese Research Group Seminar, Institute for Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-La-Neuve, Belgium, 2022
A. Halder, S. Bhandary, D. O'Regan, S. Sanvito, and A. Droghetti, Modification of Magnetic Anisotropy at Organic-Inorganic Interfaces, DPG Spring Meeting of the Condensed Matter Section 2023, Dresden, Germany, 2022
D. Lambert and D. O'Regan, First principles DFT+U+J modelling of bandgaps and defect levels in TiO2, ZrO2 and HfO2, Institute of Physics conference: Dielectrics 2022, London, UK, 2022
S. Bhandary, E. Poli, G. Teobaldi, and D. D. O'Regan, Dynamical screening at the metal-molecule interfaces: a hindrance to molecular spintronic device development?, Psi-k Conference 2022, Lausanne, Switzerland, 2022
D. D. O'Regan, First-principles Hund's J correction of approximate DFT, CCP2022: 33rd IUPAP Conference on Computational Physics, Online, hosted by The University of Texas at Austin, 2022
A. Burgess, E. Linscott, and D. D. O'Regan, Comparison of Hubbard Functionals for Strongly Correlated Systems, Psi-k Conference 2022, Lausanne, Switzerland, 2022
L. MacEnulty and D. D. O'Regan, Linear Response Hubbard U and Hund's J , PAW population analysis, Heisenberg exchange coupling parameters: A three-fold investigation featuring NiO, CCP2022: 33rd IUPAP Conference on Computational Physics, Online, hosted by The University of Texas at Austin, 2022
S. Bhandary, E. Poli, G. Teobaldi and D. D. O'Regan, Dynamical screening at the metal-molecule interface: a hindrance to molecular spintronic device developments?, Joint European Magnetic Symposia 2022, Warsaw, Poland, 2022
L. MacEnulty and D. D. O'Regan, PAW+U+J mapping of NiO onto the magnetic Heisenberg model: best practices, population analysis, and spin-symmetry investigations, ETSF Young Researchers Meeting, Marseille, France, 2022
L. MacEnulty and D. D. O'Regan, First-principles PAW+U (± J) mapping of NiO onto the magnetic Heisenberg model: towards accurate exchange coupling parameters, Paris International School on Advanced Computational Materials Science (PISACMS), Paris, France, 2022
D. S. Lambert and D. D. O'Regan, Accurate modelling of oxide bandgaps and defect levels using first principles DFT+U+J, Psi-k Conference 2022, Lausanne, Switzerland, 2022
K. Elibol, C. Mangler, D. D. O'Regan, K. Mustonen, D. Eder, J. C. Meyer, J. Kotakoski, R. G. Hobbs, P. A. van Aken, T. Susi, and B. C. Bayer, Self-assembly and heteroatomic anchoring of single indium atoms and few-atom indium clusters on graphene, EUROMAT 2021, Online, 2021
D. D. O'Regan, The partner of the Hubbard U: interpretation of Hund's J in DFT+U methods, linear-response calculations for J, and the results to expect, EPFL THEOS Group & NCCR-MARVEL Seminar, Online and Lausanne, CH, 2021
D. D. O'Regan, Force calculations in density-functional theory with extra challenges: Strongly-correlated materials, multi-centre constraints, and time-evolving basis sets, American Chemical Society Fall 2021 National Meeting & Exposition, Online and Atlanta, GA, U.S.A., 2021
D. D. O'Regan, O. K. Orhan, G. Moynihan, E. B. Linscott, D. J. Cole, and G. Teobaldi, The partner of the Hubbard U: interpretation of Hund's J in DFT+U methods, Psi-k School "Bridging First-Principles Calculations and Effective Hamiltonians", Online, hosted by IIT Genova, IT, 2021
L. MacEnulty and D. D. O'Regan, Calculation of the Magnetostatic Dipole-Dipole Correction to Periodic Spin-Density Functional Theory Using an Auxiliary Magnetic Charge Density, Materials Research Society (MRS) MRS Spring Meeting and Exhibit, Online, 2021
D. D. O'Regan, O. K. Orhan, E. B. Linscott, G. Moynihan, and G. Teobaldi, A linear-response approach for first-principles Hund's J parameters: insights, oxides, and self-consistency, APS March Meeting, Online and Chicago, IL, U.S.A., 2021
Elibol, Kenan, Mangler, Clemens, O'Regan, David D., Mustonen, Kimmo, Eder, Dominik, Meyer, Jannik C., Kotakoski, Jani, Hobbs, Richard G., van Aken, Peter A., Susi, Toma, Bayer, Bernhard C., Single indium atoms and few-atom indium clusters anchored onto graphene via silicon heteroatoms, Microscopy and Microanalysis, 27, (S1), Cambridge University Press , 2021, pp3346-3347
D. P. Gavin and D. D. O'Regan, Quantum-mechanical computational screening and design of resilient plasmonic alloys for ICT and sensing, AMBER ICT Theme Meeting, Trinity College Dublin, IE, 2021
L. MacEnulty and D. D. O'Regan, Hubbard U and Hund's Coupling J Parameters from First Principles: Towards accurate Heisenberg exchange coupling parameters for NiO, QUOROM-V, Online, 2021
L. MacEnulty and D. D. O'Regan, On using an auxiliary magnetic charge density to calculate the magnetostatic dipole-dipole correction to spin-density functional theory (DFT), EUROMAT 2021, Online, 2021
D. Lambert and D. D. O'Regan, Systematic Evaluation of First Principles DFT+U+J Algorithms for the Fast and Accurate Modelling of Transition Metal Oxides, MRS Fall Meeting and Exhibit, Online and Boston, MA, U.S.A., 2021
S. Roychoudhury (speaker), S. Sanvito, and D. D. O'Regan, Neutral Excitation Density Functional Theory (won Best Oral Presentation award), Evolution of Electronic Structure Theory and Experimental Realization, Online, organised by SRM IST KTR (India), IIT Madras (India) and Uppsala University (Sweden), 2020
D. P. Gavin, O. K. Orhan, and D. D. O'Regan, Simulation protocols for paramagnetic transition-metal oxides", Total Energy and Force Methods 2020, Donostia-San Sebastián, ES, 2020
D. P. Gavin, O. K. Orhan, and D. D. O'Regan, Corrective first-principles approaches for paramagnetic transition-metal oxides, Computational School on Electronic Excitations in Novel Materials Using the Yambo Code, Trieste, IT, 2020
K. Elibol, C. Mangler, D. D. O'Regan, K. Mustonen, D. Eder, J. C. Meyer, J. Kotakoski, R. G. Hobbs, T. Susi, and B. C. Bayer, Indium Oligomers anchored via Silicon Heteroatoms onto Graphene, Microscopy Society of Ireland Symposium, Dublin, IE, 2020
D. D. O'Regan, Through thick and thin: A size-thickness power law for liquid-phase exfoliated 2D nanosheets, Materials & Molecular Modelling Hub Conference and User Meeting, University College London, U.K., 2019
S. Roychoudhury, D. D. O'Regan, and S. Sanvito, Evaluation of Pulay forces due to change in overlap of subspace-projection orbitals in constrained DFT: Application in calculation of reorganization energy of adsorbed molecule, APS March Meeting, Boston, MA, U.S.A. , 2019
D. D. O'Regan, G. Moynihan, O. K. Orhan, E. B. Linscott, M. C. Payne, G. Teobaldi, and D. J. Cole, Towards automated self-correction of approximate DFT using first-principles Hubbard U and Hund's J parameters, Electronic Structure Discussion Group, University of Cambridge, Cambridge, U.K., 2019
S. Roychoudhury, D. D. O'Regan, and S. Sanvito, Pulay Forces with Constrained DFT: Calculation of Reorganization Energy, ONETEP Masterclass 2019: Karl Wilkinson Prize talk, Warwick, UK, 2019
D. D. O'Regan, G. Moynihan, E. B. Linscott, O. K. Orhan, G. Teobaldi, D. J. Cole, M. C. Payne, Towards an automated self-correction protocol for approximate DFT: facile first-principles Hubbard U and Hund's J parameters for arbitrary subspaces, Computational Molecular Science Conference, Warwick, U.K., 2019
D. D. O'Regan, Challenges in quantum materials simulation meet challenges in green energy, Dublin University Physical Society, Trinity College Dublin, IE, 2019
S. Roychoudhury, S. Sanvito, and D. D. O'Regan, Excitonic DFT: An Efficient and Flexible Constrained DFT Approach for Simulating Neutral Excitations in Isolated and Periodic Systems, APS March Meeting, Los Angeles, CA, U.S.A., 2018
D. D. O'Regan, An introduction to modern scholarly publication, Trinity Student Scientific Review IV Launch, Trinity College Dublin, IE, 2018
D. D. O'Regan, G. Moynihan, O. K. Orhan, E. B. Linscott, M. C. Payne, G. Teobaldi, and D. J. Cole, Self-consistent Hubbard U and Hund's J parameters for DFT from ground-state tracking linear response, New Generation in Strongly Correlated Electrons Systems, Donostia-San Sebastián, ES, 2018
K. Walshe, S. Bozhko, B. Walls, K. Zhussupbekov, D. D. O'Regan, and I.V. Shvets, Surface Defects on Cu (111): A combined STM & DFT study, 34th European Conference on Surface Science, Aarhus, DK, 2018
D. D. O'Regan, G. Moynihan, O. K. Orhan, and G. Teobaldi, A self-contained linear-response approach to constrained DFT, DFT+U, and TDDFT+U, EPFL THEOS Group & NCCR-MARVEL Seminar, Lausanne, CH, 2017
O. K. Orhan and D. D. O'Regan, A Hubbard U based correction method for exciton binding in neutral excitations: TDDFT+U, DPG Spring Meeting, Dresden, DE, 2017
E. Linscott, D. Cole, D. O'Regan, C. Weber, and M. Payne, Electronic Correlation in Biology: advances and applications of linear-scaling DFT, DFT+U, and DMFT, Autumn School in Correlated Electrons, Forschungszentrum Jülich, Germany, 2017
D. D. O'Regan, G. Moynihan, O. K. Orhan, and G. Teobaldi, Linear-Scaling direct-minimization approaches for orbital-based constrained DFT, DFT+U, and beyond, Chair of Theoretical Chemistry Seminar, TU München, Munich, DE, 2017
D. D. O'Regan, Hilbert space partitoning and Pulay forces in first-principles simulations using variable basis functions, E-CAM Workshop on Quantum MD, University College Dublin, IE, 2017
G. Moynihan, G. Teobaldi, and D. D. O'Regan, The inapplicability of exact constraints, and a minimal two-parameter DFT+U generalisation, for self-interaction error correction, DPG Spring Meeting, Dresden, DE, 2017
G. Moynihan, S. Sanvito, and D. D. O'Regan, Strain-induced Weyl and Dirac states and direct- indirect gap transitions in group-V materials, SFI AMBER Centre International Site Review, Dublin, IE, 2017
E. Linscott, D. Cole, D. O'Regan, C. Weber, and M. Payne, Electronic Correlation in Biology: advances and applications of linear-scaling DFT, DFT+U, and DMFT, 5th Annual CCP-BioSim Conference: Frontiers of Biomolecular Simulation, Southampton, U.K., 2017
G. Moynihan, G. Teobaldi, and D. D. O'Regan, An optimisability proof for self-consistent constrained DFT, and its implications for constraint-based self-interaction error correction, DPG Spring Meeting, Dresden, DE, 2017
D. D. O'Regan and E. Artacho, Diffeogeometric compensation for basis set evolution in quantum atomistic simulations, Irish Quantum Foundations Conference, University College Dublin, IE, 2017
D. D. O'Regan, G. Moynihan, and G. Teobaldi, "Optimizing constraints and corrections in approximate DFT, 17th International Conference on Density-Functional Theory and its Applications, Tällberg, SE, 2017
D. D. O'Regan and N. Marzari, DFT+U(ω): Frequency-dependent Hubbard U correction, Physics Institute, Universidade Federal Fluminense, Niteroí, BR, 2017
A. Lunghi, S. Sanvito, and D. D. O'Regan, Towards multi-scale high-throughput calculations of thermal and mechanical properties in transition-metal alloys, DPG Spring Meeting, Dresden, DE, 2017
D. D. O'Regan, G. Moynihan, O. K. Orhan, E. B. Linscott, and G. Teobaldi, A ground-state tracking linear-response method for the self-consistent Hubbard U applied to oxides, coordination complexes, and excitations, Theory and Simulation of Condensed Matter Seminar, King's College London, London, U.K., 2017
D. D. O'Regan, Developments in linear-scaling DFT for theoretical spectroscopy and Mott- Hubbard physics in disordered systems, Workshop on Research Collaboration FAPESP-Trinity, São Paulo, BR, 2017
D. D. O'Regan and N. Marzari, DFT+U(ω): Frequency-dependent Hubbard U correction, APS March Meeting, Baltimore, MA, U.S.A., 2016
G. Moynihan, G. Teobaldi, and D. D. O'Regan, Comparison of self-consistent DFT+U approaches via direct minimisation, CECAM Workshop: What about U? - Effects of Hubbard Interactions and Hund's Coupling in Solids, Trieste, IT, 2016
G. Moynihan, G. Teobaldi, and D. D. O'Regan, Self-consistent calculation of Hubbard U parameters within linear-scaling DFT, APS March Meeting, Baltimore, MA, U.S.A., 2016
O. K. Orhan and D. D. O'Regan, Towards accurate optical spectra of bulk gold via first-principles methods, Irish Atomistic Simulators Meeting, University College Dublin, IE, 2016
E. Linscott, D. Cole, D. O'Regan, C. Weber, and M. Payne, Describing Correlation Effects in Biological Systems, Physics by the Lake, Windsor, U.K., 2016
E. Linscott, D. Cole, D. O'Regan, C. Weber, and M. Payne, Describing Correlation Effects in Biological Systems, CCP9 Young Researchers Event, York, U.K., 2016
G. Moynihan and David D. O'Regan, Electronic and Mechanical Properties of Layered Pnictogen Materials, Irish Atomistic Simulators Meeting, University College Dublin, IE, 2016
D. D. O'Regan, Maintaining stability under orbital optimization in linear-scaling DFT: a long- standing problem addressed using differential geometry, CECAM Workshop: Mathematical and Numerical Analysis of Electronic Structure Models, Roscoff, FR, 2016
D. D. O'Regan and N. Marzari, Bandwidth renormalization and satellites in SrVO3 from a minimal DFT+U inspired model, ETSF Workshop on Electronic Excitations, Lund, SE, 2016
D. D. O'Regan, Quantum-mechanical simulation from the atoms up: opportunities and challenges, Dublin University Physical Society, Dublin, IE, 2016
D. D. O'Regan and A. M. Delaney, Investigation of the theory of angular momentum used in the quantum mechanical simulation of magneto-optical spectroscopy, Irish Atomistic Simulators Meeting, University College Dublin, IE, 2016
G. Moynihan and David D. O'Regan, Electronic and Mechanical Properties of Layered Pnictogen Materials, Psi-k Conference 2015, Donostia-San Sebastián, ES, 2015
David D. O'Regan, 'Notes for users of DFT+U(+J) in ONETEP', 2015, -
G. Moynihan and D. D. O'Regan, Ab Initio Simulation of Enhanced Phosphorus-based Nano-composite Materials, ETSF Young Researchers Meeting, Paris, FR, 2015
G. Teobaldi, D. D. O`Regan, N. D. Hine, and A. A. Mostofi, Self-consistent projector constrained density functional theory in ONETEP, 249th National Meeting of the American Chemical Society, Denver, CO, U.S.A., 2015
D. Cole, G. Lever, L. Lee, C. Weber, D. D. O'Regan, N. Hine, A. Chin, C.-K. Skylaris, and M. Payne, Applications of Large-Scale Electronic Structure Calculations in Biology, Psi-k Conference 2015, Donostia-San Sebastián, ES, 2015
D. D. O'Regan and N. Marzari, DFT+U(w): a pragmatic approach for calculating and incorporating dynamical Hubbard U corrections in band-structures and beyond, Materials Theory Group Seminar, Tyndall Institute, Cork, IE, 2015
G. Moynihan and D. D. O'Regan, Ab Initio Simulation of Enhanced Phosphorus-based Nano-composite Materials, International Workshop on Computational Physics and Materials Science, Trieste, IT, 2015
O. K. Orhan and D. D. O'Regan, First-principles simulation of optical spectra in gold-based alloys, International Workshop on Computational Physics and Materials Science, Trieste, IT, 2015
E. Linscott, D. Cole, D. O'Regan, N. Hine, and M. Payne, Correlation Effects in the Electronic Structure of PSII, Psi-k Conference 2015, Donostia-San Sebastián, ES , 2015
O. K. Orhan and D. D. O'Regan, The optical properties of gold and its alloys via GW and TDDFT, Psi-k Conference 2015, Donostia-San Sebastián, ES, 2015
D. D. O'Regan and N. Marzari, Frequency-dependent Hubbard U corrections: a viewpoint from density-functional theory, Condensed Matter Theory Group Seminar, University of Warwick, Warwick, UK, 2015
G. Moynihan, D. O'Regan, C. Cucinotta, and S. Sanvito, Mechanical Properties of Monolayer Black Phosphorus and the effect of van der Waals Forces, ETSF Young Researchers Meeting, Rome, IT, 2014
G. Moynihan, C. Cucinotta, S. Sanvito, and D. D. O'Regan, First Principles Simulation of Monolayer Black Phosphorus, Flatlands: Beyond Graphene, Trinity College Dublin, IE, 2014
D. D. O'Regan, Large, strongly-correlated systems simulated with linear-scaling DFT: recent developments and applications from oxides to biology, Irish Atomistic Simulators Meeting, Belfast, NI, 2014
G. Teobaldi, B. J. Morgan, D. D. O'Regan, N. D. M. Hine, and A. A. Mostofi, Subspace-corrected functionals for linear-scaling density functional theory simulation of extended energy storage interfaces, 248th National Meeting of the American Chemical Society, San Francisco, CA, U.S.A., 2014
D. D. O'Regan and N. Marzari, Frequency-dependent Hubbard U corrections to DFT beyond the random-phase approximation, Physics at the Nanoscale Seminar, King's College London, U.K., 2014
D. D. O'Regan, Linear-scaling DFT+U and DFT+DMFT or: How I learned to stop worrying and love nonorthogonality, Cecam Workshop: What about U?, Lausanne, CH, 2014
D. D. O'Regan, Revisiting a lesser-known idea of Jules Verne, discussed in his 1889 novel "Sans dessus dessous", Dublin University Physical Society, Dublin, IE, 2014
G. Moynihan, D. O'Regan, C. Cucinotta, and S. Sanvito, Mechanical Properties of Monolayer Black Phosphorus and the effect of van der Waals Forces , Irish Atomistic Simulators Meeting, Belfast, NI, 2014
G. Moynihan, C. Cucinotta, S. Sanvito, and D. D. O'Regan, First Principles Simulation of Monolayer Black Phosphorus, Hermes Summer School, London, U.K., 2014
D. D. O'Regan, (Invited) The O'Regan group in Condensed Matter Theory at TCD School of Physics, SFI AMBER Centre launch event and CRANN Research Day, Dublin, IE, 2013
G. Teobaldi, D. D. O'Regan, N. D. M. Hine, and A. A. Mostofi, Linear-scaling approaches to charge- and energy-transfer in (extended) photo-electro-chemical interfaces, Donostia International Physics Centre Seminar, Donostia-San Sebastián, ES, 2013
D. D. O'Regan and N. Marzari, Frequency-dependent Hubbard U corrections to DFT: A simple approach, 16th International Workshop on Computational Physics and Materials Science: Total Energy and Force Methods, Trieste, Italy, 2013
D. D. O'Regan, Modelling dynamically correlated materials in realistic nanostructures: DFT strategies, and linear-scaling approaches, Collaborative Conference on Materials Research (CCMR), Jeju Island, South Korea, 2013
D. D. O'Regan and N. Marzari, A new approach to treating dynamically screened interactions in low-energy corrections to density-functional theory, Department of Physics Seminar, University of Fribourg, CH, 2013
D. D. O'Regan and N. Marzari, A simplified approach for dynamical Hubbard corrections to DFT, DPG Spring Meeting: Frontiers of Electronic Structure Theory, Regensburg, DE, 2013
D. D. O'Regan and N. Marzari, Simulating correlated electrons in realistic systems: new approaches, School of Physics Seminar, Trinity College Dublin, IE, 2013
D. D. O'Regan, Electronic structure simulations in the large scale and correlated-electron regimes, Molecular Foundry Seminar, Lawrence Berkeley National Laboratory, Berkeley, CA, U.S.A., 2013
A. A. Mostofi, D. D. O'Regan, L. Andrinopoulos, N. D. M. Hine, and M. C. Payne, Strong correlations and dispersion interactions with non-orthogonal local orbitals", CECAM Workshop on localised orbitals, Cambridge, UK, 2012
Cole, D. J., O'Regan, D. D., Lee, L. P., Chau, P. L., Skylaris, C. K., Payne, M. C., Biomolecular simulation with the linear-scaling DFT code ONETEP, Abstracts of papers of the American Chemical Society, 11th International Biorelated Polymer Symposium / 243rd National Spring Meeting of the American-Chemical-Society (ACS), San Diego, CA, U.S.A. , 243, 2012, pp1
G. Teobaldi, L. J. Hardwick, D. D. O'Regan, N. D. M. Hine, and A. A. Mostofi, Constrained Density Functional Theory in ONETEP, Spring Meeting of the International Society of Electrochemistry, Washington D.C., U.S.A., 2012
G. Teobaldi, D. D. O'Regan, N. D. M. Hine, and A. A. Mostofi, Projector self-consistent constrained DFT, CECAM Workshop on localised orbitals, Cambridge, U.K., 2012
D. D. O'Regan, S. M.-M. Dubois, P. Umari, and P. D. Haynes(ed.), Efficient localised orbitals for large systems, strong correlations and excitations, Psi-k Newsletter, Cambridge, U.K., 113, Psi-k Organisation, 2012, 11-24 p
D. D. O'Regan, N. D. M. Hine, M. C. Payne, and A. A. Mostofi, A geometrically-motivated approach to optimisation in electronic structure calculations, Numerical Algorithms and High-Performance Computing Group Seminar,, Mathematics Department, EPFL, Lausanne, CH, 2012
Y. Fontana, D. D. O'Regan, N. Marzari, A. Fontcuberta i Morral et al., Self-assembled Quantum Dots in Core-Shell Nanowires, NCCR Quantum Science and Technology, Monte Verità, CH, 2012
C. Weber, D. D. O'Regan, N. D. M. Hine, M. C. Payne, G. Kotliar, and P. B. Littlewood, Dynamical mean-field theory applied to linear scaling density functional theory, CECAM Workshop on localised orbitals, Cambridge, U.K., 2012
A. Mostofi, D. D. O'Regan, N. D. M. Hine, and M. C. Payne, Linear-scaling DFT+U applied to hole localization and Friedel oscillations in very dilute (Ga,Mn)As, APS March Meeting, Boston, MA, 2012
D. D. O'Regan, N. D. M. Hine, M. C. Payne, and A. A. Mostofi, A linear-scaling DFT+U study of Friedel oscillations and localization in very dilute Gallium Manganese Arsenide, DPG Spring Meeting, Berlin, DE, 2012
D. D. O'Regan, Nonorthogonal Wannier function optimisation: geometric aspects and linear-scaling applications to strongly-correlated materials and spectroscopy, DIPC Seminar, University of the Basque Country, Donostia-San Sebastián, ES, 2011
D. D. O'Regan, N. D. M. Hine, M. C. Payne, and A. A. Mostofi, Decorrelating user and theory in ab initio calculations on strongly correlated materials: Projector self-consistent DFT+U for large systems, CECAM Workshop on Materials Informatics, Lausanne, CH, 2011
D. D. O'Regan, Optimised projections and tensorial invariance in methods for large and strongly-correlated systems, Materials Modelling Laboratory Seminar, Oxford University, Oxford, UK, 2011
S. M.-M. Dubois, L. Ratcliff, D.D. O'Regan et al., Prospects for linear scaling calculations beyond DFT accuracy, CECAM Workshop on GW Calculations for Complex Systems, Lausanne, CH, 2011
D. D. O'Regan, N. D. M. Hine, M. C. Payne, and A. A. Mostofi, Projector self-consistent DFT+U with linear-scaling and tensorial invariance, CECAM-ACAM Workshop on Density Functional Theory, University College Dublin, IE, 2011
D. D. O'Regan, A. A. Mostofi, and M. C. Payne, Linear-scaling and projector self-consistent DFT+U for electronic correlations in large systems, Thomas Young Centre International Review, University College London, U.K., 2010
D. D. O'Regan, Accelerating linear-scaling DFT: Differential geometry meets electronic structure theory, Thomas Young Centre, Imperial College London, U.K., 2010
D. D. O'Regan, A. A. Mostofi, and M. C. Payne, Linear-scaling and projector self-consistent DFT+U for electronic correlations in large systems, Psi-k Conference, Berlin, DE, 2010
D. D. O'Regan, M. C. Payne, and A. A. Mostofi, Linear-scaling and projector self-consistent DFT+U for electronic correlations in large systems, APS March Meeting, Portland, OR, U.S.A., 2010
D. D. O'Regan, A. A. Mostofi, and M. C. Payne, Linear scaling DFT+U with ONETEP, CCP9 Conference, Cambridge, U.K., 2009
D. D. O'Regan, A. A. Mostofi, and M. C. Payne, Wannier functions in the study of strong electronic correlations in DNA, International Workshop on DNA-based nanotechnology, Max-Planck-Institut für Physik komplexer Systeme, Dresden, DE, 2009
D. D. O'Regan, A. A. Mostofi, and M. C. Payne, Linear scaling DFT+U with ONETEP, 14th International Workshop on Computational Physics and Materials Science: Total Energy and Force Methods, Trieste, IT, 2008