# Lucas K. Wagner

Research Assistant Professor

## Primary Research Area

- Condensed Matter Physics

## Biography

Dr. Wagner received his bachelor's degree from North Carolina State University in 2002 and his PhD from the same institution in 2006. He then worked as a postdoc at Berkeley for two years, followed by a second postdoc at MIT in 2009. In 2011, he joined the physics department at Illinois as a research scientist and in 2014 became research assistant professor.

He is the leader of the QWalk project, which distributes a code that performs detailed quantum mechanical simulations from first principles. This code is used worldwide in diverse subject areas to obtain accurate quantum mechanical results for realistic models of systems. He has pioneered the use of quantum Monte Carlo on transition metal-oxide systems, as well as the use of high-throughput calculations to understand amorphous systems.

## Research Statement

I am interested in using high performance computation to simulate complex systems, and draw physical insights from those simulations. One major example of this is using quantum Monte Carlo calculations to accurately describe the wave functions of realistic models of electrons and nuclei, including the correlations that electrons have with one another. I am particularly interested in drawing conceptual information about how the electrons move in a correlated way. This research area can connect directly to experiments, since the calculations are realistic, and also connect to more coarse-grained theory, by solving for the effective physics of electronic systems.

## Semesters Ranked Excellent Teacher by Students

Semester | Course | Outstanding |
---|---|---|

Spring 2014 | PHYS 212 |

## Selected Articles in Journals

- Spin-state energetics of [Fe(NCH)6]2+: a Diffusion Monte Carlo perspective on the spin-crossover transition. Maria Fumanal, Lucas K. Wagner, Stefano Sanvito, and Andrea Droghetti. J. Chem. Theory Comput. 12 4233 (2016)
- Competing collinear magnetic structures in superconducting FeSe by first principles quantum Monte Carlo calculations. B. Busemeyer, M. Dagrada, S. Sorella, M. Casula, L.K. Wagner. Phys. Rev B 94 035108 (2016)
- Discovering correlated fermions using quantum Monte Carlo. L.K. Wagner, D.M. Ceperley. Rep. Prog. Phys. 79 094501 (2016)
- Diffusion Monte Carlo for accurate dissociation energies of 3d transition metal containing molecules. K. Doblhoff-Dier, J. Meyer, P.E. Hoggan, G-J Kroes, L.K. Wagner. J. Chem. Theory Comput., 12 2583 (2016)
- Hexagonal boron nitride and water interaction parameters. Y. Wu, L.K. Wagner, N.R. Aluru. J. Chem. Phys. 144 164118 (2016)
- Using Fluctuations of the Local Energy to Improve Many-Body Wave Functions. K.T. Williams, L. K. Wagner. Phys. Rev. E 94, 013303 (2016)
- Phase Stability and Properties of Manganese Oxide Polymorphs: Assessment and Insights from Diffusion Monte Carlo. J. A. Schiller, L. K. Wagner, E. Ertekin. Phys. Rev. B 92, 235209 (2015)
- Computational and experimental investigation of unreported transition metal selenides and sulphides. A. Narayan, A. Bhutani, S. Rubeck, J.N. Eckstein, D.P. Shoemaker, L.K. Wagner. Phys. Rev. B 94 045105 (2016)
- Towards a systematic assessment of errors in diffusion Monte Carlo calculations of semiconductors: Case study of zinc selenide and zinc oxide. J. Yu, L.K. Wagner, E. Ertekin, The Journal of Chemical Physics 143, 224707 (2015).
- Ground state of doped cuprates from first-principles quantum Monte Carlo calculations. Lucas K. Wagner. Phys. Rev. B 92, 161116 (2015).
- Density-matrix based determination of low-energy model Hamiltonians from ab initio wavefunctions. Hitesh J. Changlani, Huihuo Zheng, and Lucas K. Wagner. The Journal of Chemical Physics 143 102814 (2015)
- The interaction between hexagonal boron nitride and water from first principles. Y Wu, LK Wagner, NR Aluru The Journal of Chemical Physics 142 (23), 234702 (2015)
- Computation of the Correlated Metal-Insulator Transition in Vanadium Dioxide from First Principles. Huihuo Zheng and Lucas K. Wagner. Phys. Rev. Lett. 114, 176401(2015)
- Effect of electron correlation on the electronic structure and spin-lattice coupling of high-Tc cuprates: Quantum Monte Carlo calculations. Lucas K. Wagner and Peter Abbamonte. Phys. Rev. B 90, 125129 (2014)
- "Quantum Monte Carlo for Ab Initio Calculations of Energy-Relevant Materials" Lucas K. Wagner. International Journal of Quantum Chemistry 114 94 (2014)
- "Point-Defect Optical Transitions and Thermal Ionization Energies from Quantum Monte Carlo Methods: Application to F-center Defect in MgO" Elif Ertekin, Lucas K. Wagner, Jeffrey C. Grossman. Phys. Rev. B 87 155210 (2013)
- "Origins of structural hole traps in hydrogenated amorphous silicon" E. Johlin, L.K. Wagner, T. Buonassisi, J.C. Grossman. Phys. Rev. Lett. 110 146805 (2013)
- "Types of single particle symmetry breaking in transition metal oxides due to electron correlation" L.K. Wagner. J. Chem. Phys. 138, 094106 (2013)
- "Tuning metal hydride thermodynamics via size and composition: Liâ€“H, Mgâ€“H, Alâ€“H, and Mgâ€“Alâ€“H nanoclusters for hydrogen storage" L. K. Wagner , E. H. Majzoub , M. D. Allendorf, and J. C. Grossman. Phys. Chem. Chem. Phys 14, 6611-6616 (2012)
- "Quantum Monte Carlo for minimum energy structures" L.K. Wagner and J.C. Grossman. Phys. Rev. Lett. 104 210201 (2010)
- "Theoretical Study of Electronic and Atomic Structures of (MnO)(n)" H. Kino, L.K. Wagner, and L. Mitas. Journal of Computational and Theoretical Nanoscience 6 2583 (2009)
- "QWalk: A quantum Monte Carlo program" L.K. Wagner, M. Bajdich, and L. Mitas. Journal of Computational Physics 228 3390 (2009)
- "A microscopic description of light induced defects in amorphous silicon solar cells" L.K. Wagner and J.C. Grossman. Phys. Rev. Lett. 101, 265501 (2008)
- "Pfaffian pairing and backflow wavefunctions for electronic structure quantum Monte Carlo" M. Bajdich, L. Mitas, L.K. Wagner, K.E. Schmidt. Phys. Rev. B 77 115112 (2008)
- "Transition Metal oxides using quantum Monte Carlo" L.K. Wagner. J. Phys.: Condens. Matter 19 343201 (2007)
- "Energetics and Dipole Moment of Transition Metal Monoxides by Quantum Monte Carlo" L.K. Wagner and L. Mitas. J. Chem Phys. 126 034105 (2007)
- "Hartree-Fock versus quantum Monte Carlo study of persistent current in a one-dimensional ring with single scatterer" P Vagner, M. Mosko, R. Nemeth, L. Wagner, and L. Mitas. Physica E 32 350 (2006)
- "Pfaffian Pairing Wave Functions in Electronic-Structure Quantum Monte Carlo Simulations" M. Bajdich, L. Mitas, G. Drobny, L. K. Wagner, and K. E. Schmidt. Phys Rev Lett 96 130201 (2006)
- "Investigation of nodes of fermionic wave functions" L. Mitas, G. Drobny,M.Bajdich, and L.K. Wagner. Condensed Matter Theories 20 423 (2006)
- "Approximate and exact nodes of fermionic wavefunctions: Coordinate transformations and topologies'' M. Bajdich, L. Mitas, G. Drobny, and L. K. Wagner. Physical Review B 72 075131 (2005)
- "A quantum Monte Carlo study of electron correlation in transition metal oxygen molecules'' L. Wagner, L. Mitas. Chemical Physics Letters 370 412 (2003)
- "Observation of a Magic Discret Family of Ultrabright Si Nanoparticles'' Belomoin, J. Therrien, A. Smith, S. Rao, R. Twesten, S. Chaieb, M. Nayfeh, L. Wagner, and L. Mitas. Applied Physics Letters 80 841 (2002)
- "Effects of Surface Termination on the Band Gap of Ultrabright Si29 Nanoparticles: Experiments and Computational Models'' G. Belomoin, E. Rogozhina, J. Therrien, P. Braun, L. Abuhassan, M. Nayfeh, L. Wagner, and L. Mitas. Physical Review B 65 193406 (2002)