# Lucas K. Wagner

## For more information

## Education

- PhD. in physics, NCSU 2006
- B.S. in physics and applied mathematics, NCSU 2002

## Biography

Prof. 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.

He has pioneered the use of many-body electronic methods, in particular quantum Monte Carlo methods, to treat interacting systems of electrons in materials. His group has used these techniques to clarify the physics of strongly correlated systems such as the high temperature superconducting cuprates and vanadium dioxide. His group has developed new techniques to derive the collective physics of interacting quantum particles from these detailed calculations using data-based techniques.

Prof. Wagner is also active in software development, to enhance the availability of quantum many-body methods. He developed the QWalk package for quantum Monte Carlo, which scales these calculations to more than 1 million threads. Recently, he has been developing the pyscf/pyqmc ecosystem for many-body quantum projects.

## Academic Positions

- Postdoctoral researcher, MIT 2009-2011
- Postdoctoral researcher, UC Berkeley 2007-2009

## Research Statement

I use high performance computation to simulate complex systems, and draw physical insights from those simulations. One primary thread 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 behave 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.

## Undergraduate Research Opportunities

Interested undergraduates should contact me to discuss projects.

## Selected Articles in Journals

- Frontiers of stochastic electronic structure calculations. Miguel A. Morales-Silva, Kenneth D. Jordan, Luke Shulenburger, Lucas K. Wagner. The Journal of Chemical Physics 154 170401 (2021)
- Excited states in variational Monte Carlo using a penalty method. S. Pathak, B. Busemeyer, J.N.B. Rodrigues, L.K. Wagner. The Journal of Chemical Physics 154 034101 (2021)
- Recent developments in the PySCF program package . Qiming Sun, Xing Zhang, Samragni Banerjee, Peng Bao, Marc Barbry, Nick S. Blunt, Nikolay A. Bogdanov, George H. Booth, Jia Chen, Zhi-Hao Cui, Janus Juul Eriksen, Yang Gao, Sheng Guo, Jan Hermann, Matthew R. Hermes, Kevin Koh, Peter Koval, Susi Lehtola, Zhendong Li, Junzi Liu, Narbe Mardirossian, James D. McClain, Mario Motta, Bastien Mussard, Hung Q. Pham, Artem Pulkin, Wirawan Purwanto, Paul J. Robinson, Enrico Ronca, Elvira Sayfutyarova, Maximilian Scheurer, Henry F. Schurkus, James E. T. Smith, Chong Sun, Shi-Ning Sun, Shiv Upadhyay, Lucas K. Wagner, Xiao Wang, Alec White, James Daniel Whitfield, Mark J. Williamson, Sebastian Wouters, Jun Yang, Jason M. Yu, Tianyu Zhu, Timothy C. Berkelbach, Sandeep Sharma, Alexander Sokolov, Garnet Kin-Lic Chan. J. Chem. Phys. 153 024109 (2020)
- Identifying materials with charge-spin physics using charge-spin susceptibility computed from first principles. J. N. B. Rodrigues, Lucas K. Wagner. J. Chem. Phys. 153 074105 (2020)
- Direct comparison of many-body methods for realistic electronic Hamiltonians Kiel T. Williams, Yuan Yao, Jia Li, Li Chen, Hao Shi, Mario Motta, Chunyao Niu, Ushnish Ray, Sheng Guo, Robert J. Anderson, Junhao Li, Lan Nguyen Tran, Chia-Nan Yeh, Bastien Mussard, Sandeep Sharma, Fabien Bruneval, Mark van Schilfgaarde, George H. Booth, Garnet Kin-Lic Chan, Shiwei Zhang, Emanuel Gull, Dominika Zgid, Andrew Millis, Cyrus J. Umrigar, Lucas K. Wagner. Physical Review X 10 011041 (2020)
- Effective spin-orbit models using correlated first-principles wave functions. Yueqing Chang and Lucas K. Wagner. Physical Review Research 2 013195 (2020)
- Many-Body Electric Multipole Operators in Extended Systems William A. Wheeler, Lucas K. Wagner, Taylor L. Hughes. Physical Review B 100 245135 (2019)
- Prediction for the singlet-triplet excitation energy for the spinel MgTi2O4 using first-principles diffusion Monte Carlo. Brian Busemeyer, Gregory J. MacDougall, Lucas K. Wagner Physical Review B 99 081118 (2019)
- High Hole Mobility and Nonsaturating Giant Magnetoresistance in the New 2D Metal NaCu4Se4 Synthesized by a Unique Pathway. Chen, Haijie; Rodrigues, Joao; Rettie, Alexander; Song, Tze-Bin; Chica, Daniel; Su, Xianli; Bao, Jin-Ke; Chung, Duck Young; Kwok, Wai-Kwong; Wagner, Lucas; Kanatzidis, Mercouri J. Am. Chem. Soc. 141 635 (2018)
- Non-orthogonal determinants in multi-Slater-Jastrow trial wave functions for fixed-node diffusion Monte Carlo. Shivesh Pathak and Lucas K. Wagner J. Chem. Phys. 149, 234104 (2018)
- Uncovering anisotropic magnetic phases via fast dimensionality analysis. Manohar H. Karigerasi, Lucas K. Wagner, and Daniel P. Shoemaker. Phys. Rev. Materials 2, 094403 (2018)
- From real materials to model Hamiltonians with density matrix downfolding. Huihuo Zheng, Hitesh J. Changlani, Kiel T. Williams, Brian Busemeyer, Lucas K. Wagner Frontiers in Physics (2018)
- Quantum Monte Carlo study of the metal to insulator transition on a honeycomb lattice with 1/r interactions. Li Chen, Lucas K. Wagner. Phys. Rev. B 97 045101 (2018)
- Semiconducting Ba3Sn3Sb4 and Metallic Ba(7-x)Sn11Sb(15-y) (x=0.4,y=0.6) Zintl Phases. Haijie Chen, Awadhesh Narayan, Canstantinos Stoumpos, Jing Zhao, Fei Han, Duck Young Chung, Lucas K. Wagner, Wai-Kwong Kwo, and Mercouri G. Kanatzidis. Inorganic Chemistry 56 14251 (2017)
- The importance of sigma bonding electrons for the accurate description of electron correlation in graphene. Huihuo Zheng, Yu Gan, Peter Abbamonte, Lucas K. Wagner Physical Review Letters 119 166402 (2017)
- Charge Density Wave and Narrow Energy Gap at Room Temperature in Pb3-xSb1+xS4Te2-Ã‚Â½ with Square Te Sheets. Haijie Chen, Cristos D. Malliakas, Awadhesh Narayan, Lei Fang, Duck Young Chung, Lucas K. Wagner, Wai-Kwong Kwok, Mercouri G. Kanatzidis. J. Am. Chem. Soc. 139 11271 (2017)
- Investigation of a Quantum Monte Carlo Protocol To Achieve High Accuracy and High-Throughput Materials Formation Energies Kayahan Saritas, Tim Mueller, Lucas Wagner, Jeffrey C. Grossman J. Chem. Theory Comput. 13 1943 (2017)
- Accurate barrier heights using diffusion Monte Carlo Kittithat Krongchon, Brian Busemeyer, Lucas K. Wagner The Journal of Chemical Physics 146 124129 (2017)
- Fixed node diffusion Monte Carlo description of nitrogen defects in zinc oxide. Jaehyung Yu, Lucas K. Wagner, and Elif Ertekin. Phys. Rev. B 95 075209 (2017)
- 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)

## Invited Lectures

- Understanding strongly correlated systems using quantum Monte Carlo
- Exploring High Tc Using Quantum Monte Carlo
- The interrelated physics of magnetism, delocalization, and electron correlation in materials
- Directly simulating electron correlations in realistic models of strongly interacting materials
- Can we understand high-Tc superconductors from first principles?

## Magazine Articles

## Other Scholarly Activities

- Maintainer for pyQMC python quantum Monte Carlo package (http://github.com/WagnerGroup/pyqmc)

## Teaching Honors

- Nordsieck award for teaching excellence in physics (Spring 2020)

## Recent Courses Taught

- CSE 498 DM - Intro to Digital Materials
- ME 598 DM - Intro to Digital Materials
- MSE 598 DM - Intro to Digital Materials
- PHYS 213 - Univ Physics: Thermal Physics
- PHYS 214 - Univ Physics: Quantum Physics
- PHYS 460 - Condensed Matter Physics