Sam's paper, with Rob Webber and Jonathan Weare of NYU, Beyond Walkers in Stochastic Quantum Chemistry: Reducing Error using Fast Randomized Iteration, is posted to the arXiv - the group's first foray into QMC!
Alan's paper, Vertex Corrections to the Polarizability Do Not Improve the GW Approximation for the Ionization Potential of Molecules, is published in J. Chem. Theory Comput.
Congratulations to James for being selected to receive a 2019 NSF Graduate Research Fellowship! UPDATE: And the National Defense Science and Engineering Graduate Fellowship (NDSEG)! Tough choice.
Happy International Women's Day! Here's Yeongsu presenting her work on excitons in Ruddlesden-Popper perovskites at the APS March Meeting. According to IPEDS and the APS, only 40% of PhDs in chemistry and 20% of PhDs in physics are earned by women. Many resources available from the ACS Women Chemists Committee, the APS Women in Physics initiative, and the APS STEP UP 4 Women program.
At the APS March meeting, kicking off our Focus Session, "Periodic quantum chemistry beyond DFT," co-organized with Garnet Chan. Sessions include "DFT, embedding, and beyond," "Quantum Monte Carlo," and "Wavefunction methods."
Xiao Wang joins CCQ as a Flatiron Research Fellow. Previously, Xiao received his Ph.D. with Fritz Schaefer at the University of Georgia and was a postdoc with Ed Valeev at Virginia Tech. Welcome Xiao!
Random-phase approximation excitation energies from approximate equation-of-motion coupled-cluster doubles is selected for the 2018 JCP Editors' Choice, "a few of the many notable JCP articles of 2018 that present significant and definitive research in experimental and theoretical areas of the field."
The group is moving to New York City! Tim has accepted a joint position in the Department of Chemistry at Columbia University and the newly-established Center for Computational Quantum Physics at the Flatiron Institute, a division of the Simons Foundation.
Alan's second paper in as many weeks - this time, plasmon excitations in metals from equation-of-motion coupled-cluster theory. Ab Initio Lifetime and Concomitant Double-Excitation Character of Plasmons at Metallic Densities is posted to the arXiv.
Tim's paper with Roel Tempelaar, Many-Body Simulation of Two-Dimensional Electronic Spectroscopy of Excitons and Trions in Monolayer Transition-Metal Dichalcogenides, is posted to the arXiv.
Combining wavefunction-based quantum chemistry with Green's function techniques: Alan's paper, Vertex corrections to the polarizability do not improve the GW approximation for molecules, is posted to the arXiv.
Tim's paper, Random-phase approximation excitation energies from approximate equation-of-motion coupled-cluster doubles, is published as a Communication in J. Chem. Phys. and selected as an Editor's Pick.
Malte's paper, On the Relation Between Equation-of-Motion Coupled-Cluster Theory and the GW Approximation, is published in J. Chem. Theory Comput.!
Really going to miss having this guy in the group. Good luck at Caltech, Shi-Ning!
Shi-Ning presents his undergraduate thesis, "Classical and quantum theories for screened Coulomb interactions" and is chosen to receive the Norman H. Nachtrieb Memorial Award for Excellence in Undergraduate Studies in Chemistry. Congrats Shi-Ning!
Congratulations to Sam, maybe the first theoretical chemistry student to win the Gerhard Closs Teaching Award in Organic Chemistry!
Malte's paper, On the Relation Between Equation-of-Motion Coupled-Cluster Theory and the GW Approximation, appears on the arXiv. They're not as different as you may think! IP/EA-EOM-CCSD contains (most of) the physics described by the GW approximation, but many additional effects that improve the accuracy.
Congratulations to Jonathan and Malte, who have been selected as 2018 NSF Graduate Research Fellows!
Tim's paper, Random-phase approximation excitation energies from approximate equation-of-motion ring coupled-cluster doubles, is posted to the arXiv.
Many thanks to the students of BU, MIT, and Harvard, who hosted Tim for the Greater Boston Area Theoretical Chemistry Lecture Series and three exciting days of scientific discussions.
Yeongsu's paper, Environmentally sensitive theory of electronic and optical transitions in atomically thin semiconductors, is published as a Rapid Communication in Phys. Rev. B, and selected as an Editors' Suggestion!
Congratulations to Yeongsu, Jonathan, and Malte, who have all passed their second-year candidacy exams!
Jonathan's paper, Linear and nonlinear spectroscopy from quantum master equations, is published in J. Chem. Phys.
Two new graduate students join the group! Welcome to Sam Greene (B.S. UChicago, M.Sc. Oxford), who will be jointly advised by Jonathan Weare (UChicago Statistics), and James Callahan (B.A. Harvard).
Tim is selected for the US Air Force Young Investigator Program (YIP), which will fund our work on exciton interactions in semiconductor nanostructures. The objective of the Air Force YIP is "to foster creative basic research in science and engineering, enhance early career development of outstanding young investigators, and increase opportunities for the young investigators to recognize the Air Force mission and the related challenges in science and engineering."
Alan Lewis (D. Phil. Oxford University) joins the group as a postdoctoral researcher. Welcome, Alan!
Quantum master equations: time-tested classics for single-time observables, but how good are they for multi-time correlation functions, like the ones probed in spectroscopy? Read Jonathan's paper, Linear and nonlinear spectroscopy from quantum master equations, to find out!
Can we use atomically-thin semiconductors as optical sensors of the local chemical environment? Read Yeongsu's paper, Environmentally-Sensitive Theory of Electronic and Optical Transitions in Atomically-Thin Semiconductors, to find out why it's harder than you think!
Farewell to pseudopotentials! Gaussian and plane-wave mixed density fitting for periodic systems has been posted to the arXiv.
We have received a Start-Up Research Grant from the US-Israel Binational Science Foundation to study the role of low-frequency nuclear fluctuations in soft semiconductors in collaboration with Omer Yaffe's group at the Weizmann Institute!
Bryan Lau (Ph.D. Northwestern University) joins the group as a postdoctoral researcher. Welcome, Bryan!
Malte receives the Nathan Sugarman Teaching Award in General Chemistry!
University of Chicago undergraduate Shi-Ning Sun joins the group!
Tim visits nearby Northwestern and gives a talk at the Northwestern-Argonne Solar Energy Research Center (ANSER).
Tim and Greg Scholes organize a Focus session on Spectroscopy and Dynamics of Multichromophore Systems at APS March Meeting.
Gaussian-Based Coupled-Cluster Theory for the Ground State and Band Structure of Solids has been accepted for publication in the Journal of Chemical Theory and Computation.
We contribute to the open-source PySCF software package, especially concerning excited-state and condensed-phase electronic structure. A preprint describing the capabilities and design philosophy of PySCF has been posted to the arXiv: The Python-based Simulations of Chemistry Framework (PySCF).
Tim gives an invited talk at the 18th Total Energy and Force Methods workshop, held at ICTP.
Fellow at PCTS (2014-2016)
Ph.D. Columbia University (2014)
B.A. NYU (2009)
NDSEG Fellow (2019-2022)
B.A. Harvard University (2014)
B.A. Seoul National University (2015)
NSF Graduate Research Fellow (2018-2021)
B.A. Rutgers University (2016)
M.S. Oxford University (2016)
Rhodes Scholar (2014-2016)
B.S. University of Chicago (2014)
NSF Graduate Research Fellow (2018-2021)
B.S. University of Washington (2016)
Ph.D. Northwestern University (2017)
B.S. University of Toronto (2011)
D.Phil. Oxford University (2017)
M.Chem. Oxford University (2013)
Postdoc Virginia Tech (2016-2018)
Ph.D. University of Georgia (2016)
B.S. Beihang University (2012)
Ph.D. student, Caltech (Chan group)
We work on a variety of quantum-mechanical problems motivated by excited-state phenomena. This research occurs at the fascinating interface of physical chemistry, condensed-matter physics, and materials science.
Building on modern theories of quantum dynamics, we develop powerful simulation techniques for nonequilibrium and time-resolved spectroscopies. These new tools enable the accurate simulation of extremely large and complex sytems, providing new insights into excited-state structure and dynamics.
We are actively exploring the excited-state behavior of fundamentally interesting and technologically promising materials, especially those that are anisotropic, layered, or low-dimensional. Particular materials of interest include conjugated polymers, organic molecular crystals, and quasi-two-dimensional inorganic semiconductors.
Aiming towards highly accurate but insightful descriptions of electronic excitations, we formulate and apply electronic structure methods adapted for the condensed phase. Some of our favorite tools are low-energy effective theories, many-body diagrammatics, and coupled-cluster techniques.
Organic materials expert Jonathan explains the science of polymers, found everywhere in our daily lives, and runs a hands-on demo of polymer cross-linking in sodium alginate.
James sparks a student discussion about electronic conductors and insulators, as well as circuits, lightbulbs, and light-emitting diodes.
Timothy Berkelbach is an Assistant Professor in the Department of Chemistry at Columbia University and a Research Scientist in the Center for Computational Quantum Physics at the Flatiron Institute. From 2016 to 2018, he was the Neubauer Family Assistant Professor in the Department of Chemistry and the James Franck Institute at the University of Chicago. He received his B.A. in physics and chemistry from NYU in 2009 and his Ph.D. in chemical physics from Columbia University in 2014, where he was a Department of Energy Office of Science Graduate Research Fellow advised by David Reichman. Tim then spent two years as a fellow of the Princeton Center for Theoretical Science, working closely with Garnet Chan. Since starting his independent career, Tim has been named an AFOSR Young Investigator, an Alfred P. Sloan Research Fellow, and a recipient of the NSF CAREER award.
3000 Broadway, 518 Havemeyer Hall, New York NY 10027
162 Fifth Avenue, Office 901, New York NY 10010
1 646 876 5930
Diverse problems require diverse teams. We welcome students and postdocs of all genders, races, ages, sexual orientations, and disability statuses. If you're interested in joining us in one of the most multicultural cities in the world, contact Tim for more information on the graduate program at Columbia or postdoctoral openings at Columbia or the Flatiron Institute.