Recent news

Jun 2019

Congratulations to Sam, who was selected as a 2019 MolSSI Seed Software Fellow!

May 2019

Welcome to our summer researchers, Sylvia Bintrim and James Smith! Sylvia is an incoming PhD student at Columbia and an NSF Graduate Research Fellow. James is a summer intern at CCQ, visiting from CU Boulder, where he is a PhD student in the Sharma group.

May 2019

A collaboration long in the making: Coupled-cluster impurity solvers for dynamical mean-field theory is posted to the arXiv.

May 2019

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!

Apr 2019

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.

Mar 2019

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.

Mar 2019

Honored to receive the NSF CAREER Award. Thank you to the NSF's Chemical Theory, Models and Computation Methods and Condensed Matter and Materials Theory programs for supporting our research and education efforts!

Mar 2019

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."

Feb 2019

The PySCF paper was one of the ten most downloaded articles in the past year in WIREs Computational Molecular Science.

Jan 2019

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!

Jan 2019

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."

Jan 2019

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.

Oct 2018

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.

Sep 2018

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.

Jul 2018

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.

Jul 2018

Jul 2018

Really going to miss having this guy in the group. Good luck at Caltech, Shi-Ning!

May 2018

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!

May 2018

Congratulations to Sam, maybe the first theoretical chemistry student to win the Gerhard Closs Teaching Award in Organic Chemistry!

May 2018

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.

Apr 2018

Congratulations to Jonathan and Malte, who have been selected as 2018 NSF Graduate Research Fellows!

Feb 2018

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.

Feb 2018

Very honored to be named a 2018 Sloan Research Fellow. Thank you to the Sloan Foundation for supporting our research! [UChicago News, NY Times Ad]

Jan 2018

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!

Jan 2018

Congratulations to Yeongsu, Jonathan, and Malte, who have all passed their second-year candidacy exams!

Dec 2017

Jonathan's paper, Linear and nonlinear spectroscopy from quantum master equations, is published in J. Chem. Phys.

Dec 2017

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).

Oct 2017

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."

Sep 2017

Alan Lewis (D. Phil. Oxford University) joins the group as a postdoctoral researcher. Welcome, Alan!

Sep 2017

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!

Sep 2017

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!

Jul 2017

Farewell to pseudopotentials! Gaussian and plane-wave mixed density fitting for periodic systems has been posted to the arXiv.

Jul 2017

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!

Jun 2017

Shi-Ning leaves us for the summer, to participate in the Amgen Scholars Program at Kyoto University, where he will work in the research group of Prof. Yoshitaka Tanimura. Good luck Shi-Ning!

Jun 2017

Many thanks to Ben Levine and the other organizers at MSU for hosting the excellent 49th Midwest Theoretical Chemistry Conference. We are excited to announce that the 50th MWTCC will be held in Summer 2018 at the University of Chicago. More details can be found at

May 2017

Bryan Lau (Ph.D. Northwestern University) joins the group as a postdoctoral researcher. Welcome, Bryan!

May 2017

Malte receives the Nathan Sugarman Teaching Award in General Chemistry!

May 2017

Tim heads to Europe to speak at the Theory Department of the Fritz Haber Institute in Berlin and the CECAM Workshop Theoretical Chemistry for Extended Systems in Toulouse.

Apr 2017

University of Chicago undergraduate Shi-Ning Sun joins the group!

Mar 2017

Tim visits nearby Northwestern and gives a talk at the Northwestern-Argonne Solar Energy Research Center (ANSER).

Mar 2017

Tim and Greg Scholes organize a Focus session on Spectroscopy and Dynamics of Multichromophore Systems at APS March Meeting.

Feb 2017

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.

Jan 2017

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).

Jan 2017

Tim gives an invited talk at the 18th Total Energy and Force Methods workshop, held at ICTP.

Group Members


Timothy Berkelbach

Principal Investigator

Fellow at PCTS (2014-2016)
Ph.D. Columbia University (2014)
B.A. NYU (2009)


James Callahan

Graduate Student

NDSEG Fellow (2019-2022)
B.A. Harvard University (2014)


Yeongsu Cho

Graduate Student

B.A. Seoul National University (2015)


Jonathan Fetherolf

Graduate Student

NSF Graduate Research Fellow (2018-2021)
B.A. Rutgers University (2016)


Sam Greene

Graduate Student
joint w/ J. Weare (NYU Courant)

M.S. Oxford University (2016)
Rhodes Scholar (2014-2016)
B.S. University of Chicago (2014)


Malte Lange

Graduate Student

NSF Graduate Research Fellow (2018-2021)
B.S. University of Washington (2016)


Bryan Lau

Postdoctoral Researcher

Ph.D. Northwestern University (2017)
B.S. University of Toronto (2011)


Alan Lewis

Postdoctoral Researcher

D.Phil. Oxford University (2017)
M.Chem. Oxford University (2013)


Xiao Wang

Flatiron Research Fellow

Postdoc Virginia Tech (2016-2018)
Ph.D. University of Georgia (2016)
B.S. Beihang University (2012)

Shi-Ning Sun

Undergraduate Student

Ph.D. student, Caltech (Chan group)

Research areas

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.

Quantum dynamics and spectroscopy

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.

Emerging materials

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.

Condensed-phase electronic structure

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.

Interested in learning more?

Check out our publications!


Berkelbach group members, in collaboration with the MRSEC at the University of Chicago, organize and run a weekly colloquium, "Modern Materials Technology", at the nearby Lindblom Math and Science Academy.

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.

About Tim

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.

Columbia University

3000 Broadway, 518 Havemeyer Hall, New York NY 10027

Flatiron Institute

162 Fifth Avenue, Office 901, New York NY 10010

1 646 876 5930

Join us!

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.