News

umIn June, our group was pleased to welcome Lyuben Borislavov from the University of Sophia in Sophia, Bulgaria, where he was recommended by Professors Alia Tadjer and Todor Dudev, and Erica Mitchell from Taylor University in Upland Indiana, where she was recommended by Professor T. Brandon Magers. Erica  worked on the multi-configuration pair-density functional theory of Diels-Alder reactions and the speedup of MC-PDFT analytic gradients, co-supervised by Professor Laura Gagliardi and also aided by Thais Scott, Jie Bao, and Matt Hermes. Lyuben worked on machine learning of molecular dynamics trajectories for the photodissociation of thioanisole, aided by Kelsey Parker and Yinan Shu. Both students presented their work at the 2019 Summer Undergraduate Research Fellowship Symposium (SURF Symposium) of CTC on August 6: The speakers were 

  Lyuben Borislavov from Sofia University (Bulgaria), Don Truhlar group 

  Janey Lin from Mount Holyoke College, Massachusetts, Laura Gagliardi group

  Maria Mikhailenko from ITMO University (Russia), Jason Goodpaster group

  Erica Mitchell from Taylor University, Indiana, groups of Gagliardi and Truhlar

  Claire Shugart from Carlton College, Minnesota, Gagliardi group

  Samuel Powell from Ohio Northern University, Gagliardi group

  Victoria Vernadskaia from ITMO University (Russia), Ilja Siepmann group

  Peiyao Wu from Emory University, Georgia, Siepmann group

After the symposium the picture at the right was taken of all the summer researchers in the CTC SURF program, along with the participating mentors and advisers.

 

August 7, 2019

Postdoctroal assoicate Jingyun Ye will begin as assistant professor of Chemistry at Clarkson University in Potsdam, New York in January 2020. Here is a list of her publications so far in the Truhlar group:

jacs1“Bridging Zirconia Nodes within a Metal–Organic Framework via Catalytic Ni-hydroxo Clusters to Form Hetero-Bimetallic Nanowires," A. E. Platero-Prats, A. B. League, V. Bernales, L C. Gallington, A. Vjunov, N. M. Schweitzer, J. Ye, J. Zheng, B. L Mehdi, Z. Li, A. J. Stevens, O. K. Farha, J. T. Hupp, N. D. Browning, D. G. Truhlar, J. L. Fulton,  J. A. Lercher, D. M. Camaioni, L. Gagliardi, C. J. Cramer, K. W. Chapman, Journal of the American Chemical Society 139, 10410-10418 (2017). 

doi.org/10.1021/jacs.7b04997

 

jcatal1“Single Ni Atoms and Ni4 Clusters Have Similar Catalytic Activity for Ethylene Dimerization,” J. Ye, L. Gagliardi, C. J Cramer, and D. G Truhlar, Journal of Catalysis 354, 278–286 (2017). 

doi.org/10.1016/j.jcat.2017.08.011

 

 

 jcatal2“Computational Screening of MOF-Supported Transition Metal Catalysts for Activity and Selectivity in Ethylene Dimerization,” J. Ye, L. Gagliardi, C. J. Cramer, and D. G. Truhlar, Journal of Catalysis 360, 160-167 (2018). 

doi.org/10.1016/j.jcat.2017.12.007

 

 

acscatal“Rationalizing the Reactivity of Bimetallic Molecular Catalysts for CO2 Hydrogenation,” J. Ye, R. C. Cammarota, J. Xie, M. V. Vollmer, D. G. Truhlar, C. J. Cramer, C. C. Lu, and L. Gagliardi, ACS Catalysis 8, 4955-4968 (2018).

 doi.org/10.1021/acscatal.8b00803

 

 

jacs2“Beyond the Active Site: Tuning the Activity and Selectivity of a Metal−Organic Framework-Supported Ni Catalyst for Ethylene Dimerization,” J. Liu, J. Ye, Z. Li, K. i. Otake, Y.  Liao, A.  Peters, H. Noh, D. G. Truhlar, L. Gagliardi, C. J. Cramer, O. Farha, and J. Hupp, Journal of the American Chemical Society 140, 11174-11178 (2018). 

doi.org/10.1021/jacs.8b06006

 

jpcc1“Organic Linker Effect on the Growth and Diffusion of Cu Clusters in a Metal-Organic Framework,” J. Ye, C. J Cramer, and D. G. Truhlar, Journal of Physical Chemistry C 122, 26987-26997 (2018).

doi.og/ 10.1021/acs.jpcc.8b09178

 

February 17, 2019

The editors of PCCP (the physical chemistry journal of the Royal Society of Chemistry) have selected the paper 

        “Extended Hamiltonian Molecular Dynamics: Semiclassical Trajectories with Improved Maintenance of Zero Point Energy,” Yinan Shu, Sijia S. Dong, Kelsey A. Parker, J. Lucas Bao, Linzao Zhang, and Don Truhlar, Physical Chemistry Chemical Physics 20, 30209-30218 (2018). doi.org/10.1039/C8CP04914A

for the  the themed collection "2018 PCCP HOT Articles”.

Classical molecular dynamics is one of the most widely employed simulation tools in physical chemistry. A long-standing problem in classical molecular dynamics simulations is the inability of classical mechanics to maintain zero point energy in the vibrational modes.  There have been many attempts to overcome this deficiency, but no practical and completely satisfactory method has emerged. This article shows how the problem can be tamed by presenting a very simple extended Hamiltonian goes a long way toward solving the problem. The paper is of broad interest because the method can be applied even to the most complex problems for which classical simulations are currently employed. 

yinan

February 6, 2019 

lucasJunwei (Lucas) Bao successfully defended his Ph D. thesis on August 10, 2018.  His thesis is entitled Reaction Rate Theory, Electronic Structure Theory, and Applications; it has an introduction plus 19 chapters covering his publications. Congratulations Lucas!  Lucas will now head out to Princeton for a postdoctoral position with Professor Emily Carter.

The picture shows his committee immediately after the defense, from left to right: Tom Schwartzentruber, Don Truhlar, Lucas Bao, Aaron Massari, and Chris Cramer.

August 10, 2018 

xingpingnews.jpgPhotocatalysts can absorb light and convert the exciton into an electron–hole pair, so the electron can drive a reduction reaction and/or the hole can drive an oxidation reaction.  Photocatalysts are usually inorganic semiconductors (e.g., TiO2). Dr. Xin-Ping Wu, a postdoctoral scholar working with Don Truhlar and Laura Gagliardi, has proposed that metal–organic frameworks (MOFs) containing cerium would also be good photocatalysts.  MOFs are crystalline materials with some attractive properties for photocatalysis, including well separated inorganometallic nodes that can serve as catalytic centers and – since MOFs are nanoporous –including high accessibility of potential catalytic sites to reagents; however, the highest unoccupied and the lowest unoccupied crystal orbitals (HOCO and LUCO) of MOFs are usually localized solely on their linkers, so most MOFs have poor charge separation capabilities, which leads to short lifetimes of excited states and limits possible photocatalytic activity. But Ce has low-lying empty 4f orbitals, and Ce-MOFs can have the LUCO on Ce in the node, thereby separating the HOCO and LUCO onto different subsystems (the linker and the node) in the MOF, as shown in the figure on the right. This anticipated result was confirmed by quantum chemical calculations on a substituted UiO-66 MOF, with Zr (for stability) and Ce (for photocatalytic activity) as the metals in the nodes. With purposefully designed linkers, absorption is in the visible and the absolute orbital energies are well situated for water splitting or CO2 reduction. The work shows the power of theory in engineering the electronic properties of functional nanoporous materials.

The work is published in the Journal of the American Chemical Society [doi.org/10.1021/jacs.8b03613]. The research was supported by the Nanoporous Materials Genome Center (NMGC) [NMGC main page], which is a Computational Chemical Sciences Center in the Department of Chemistry at the University of Minnesota.

June 2, 2018

 

jingyunFebruary 20 2018

Dr. Jingyun Ye, a postdoctoral scholar in the research groups of Chris Cramer, Laura Gagliardi, and Don Truhlar, received a poster competiton award for her poster “Computational Study of MOF-Supported Metal Catalysts for Ethylene Dimerization” at the conference on New Challenges in Heterogeneous Catalysis at the King Abdullah University of Science and Technology(KAUST) in Thuwal, Saudi Arabia on January 29. The poster was coauthored by her three co-advisers and Aaron League and Varinia Bernales in our department and by four collaborators at Northwestern University, five at Pacific Northwest National Laboratory, and five at Argonne National Laboratory. The work was sponsored by the Inorganometallic Catalyst Design Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences.

Metal-organic frameworks (MOFs) with ultrahigh porosity and large surface area have recently emerged as excellent heterogeneous supports for transition metal catalysts, by either functionalization of the organic linker or direct modification of the inorganometallic nodes. NU-1000 is a mesoporous MOF of particular interest due to its chemical and thermal stability. Its coordinatively unsaturated metal sites at the inorganic nodes provide postions at which highly dispersed and isolated single-site catalytic metal oxide catalysts may be anchored, and its large pore size (~30 Å can can facilitate the diffusion of gaseous molecules to and from these catalytic sites. Through atomic layer deposition, a highly dispersed Ni catalyst (Ni-NU-1000) was successfully synthesized; it shows good activity for ethylene ethylene oligomerization but poor selectivity for 1-butene production.  

figure1

 Figure 1: (a) Structure of NU-1000, (b) and (c) the small pore of NU-1000 without and with Ni hydroxo cluster bridging between the two Zr nodes, (d) the top and side view of structure of Ni hydroxo cluster.

The poster reported computational simulations to develop a model for a Ni catalyst supported on NU-1000 and the use of this model to identify the catalytically active sites for ethylene dimerization reaction at the gas-solid interface of the MOF. The calculations show that the catalytic activity of Ni-NU-1000 for ethylene dimerization depends more strongly on the spin state of the Ni atoms than on the Ni-oxo cluster size. Furthermore, a variety of metals were screened to search for potential catalysts with increased selectivity for 1-butene production. As a result, CrII, NiII and PdII are predicted to be the most promising catalysts for ethylene dimerization.

             figure2

Figure 2: Ni supported NU-1000 for ethylene dimerization: Cluster Size vs. Spin State.

Publications:

“Single Ni Atoms and Ni4 Clusters Have Similar Catalytic Activity for Ethylene Dimerization,” J. Ye, L. Gagliardi, C.J. Cramer, and D.G. Truhlar, Journal of Catalysis 354, 278-286 (2017).

“Computational Screening of MOF-Supported Transition Metal Catalysts for Activity and Selectivity in Ethylene Dimerization,” J. Ye, L. Gagliardi, C.J. Cramer, and D.G. Truhlar, Journal of Catalysis (in press).

December 16 2017

Junwei Lucas Bao has been named as one of two recipients of the 2018 Graduate Award in Theoreticalbao Chemistry given by the American Chemical Society Physical Chemistry Division. Lucas received a B. Sc. in Chemistry from Nanjing Normal University, and he joined our group in fall 2013. Lucas is honored for his work in several areas, especially chemical kinetics – including chiral-molecule kinetics, plasma chemistry, quantum mechanical multi-dimensional tunneling along multiple paths, and the theory of pressure-dependent reactions – and for predicting bond dissociation energies of transition metal compounds by multiconfiguration pair-density functional theory and second-order perturbation theory based on correlated participating orbitals and separated pairs. Lucas will receive a monetary award and an allocation of computer time on Blue Waters Supercomputer; he will present an award lecture at the Spring National ACS Meeting in New Orleans. Congratulations Lucas!

chadCongratulations to Chad Hoyer who successfully defend his thesis today. Chad was co-advised by Professors Laura Gagliardi and Don Truhlar. His thesis is entitled "Electronic Structure Method Development for Excited-State Chemistry” and it includes research on multi-configuration pair-density functional theory for excited states and on dipole-quadrupole-electrostatic potential (DQΦ) diabatization. The picture at the right shows Laura Gagliardi, Chad Hoyer, and Don Truhlar after Chad’s defense.

Septemper 15, 2017

June 11, 2017

In June, Don TrDalian_2017uhlar was in Dalian, China to deliver the 25th Zhang Dayu Lectureship at the Dalian Institute of Chemical Physics and to give his introductory lecture as an Honorary Fellow of the Chinese Chemical Society at the 13th National Congress for Quantum Chemistry. His trip to China was hosted by Donghui Zhang and Xuefei Xu. A highlight of the trip was meeting for dinner in Dalian with the members of the WeChat group called “Truhlar group alumni”, consisting of his former students and associates In China. They were also joined by Donghui Zhang, an honorary group member (He received his degree with John Zhang, who was a student in the groups of Don Kouri and Don Truhlar, so he is a group grandalumnus.) In the picture, left to right, we see Peifeng Su, Bo Long, Guo-Liang Song, Zhen Hua Li, Shuping Huang, Don Truhlar, Wenjing Zhang, Xin Zhang, Xuefei Xu, Donghui Zhang, Chaoyuan Zhu (Taiwan), and Wei Lin.

 

Shaohong Li defended his Ph. D. thesis on May 23, 2017 with a presentation entitled “Computational Photochemistry, Spectroscopy, and Potential Energy Surfaces of Complex Molecules.” Shaohong received a B.S. from Nanjing University in 2012 and an M.S. from the University of Minnesota in 2014. The photo shows him with his committee after his Ph.D defense. From left to right: Yuichi Kubota, Shaohong Li, Don Truhlar, Chris Cramer, and Ilja Siepmann.shaohong Li

Shaohong’s work in our group includes several projects, including

  • improving Kohn-Sham density functional theory and density functionals for molecular Rydberg states
  • partial atomic charges in inorganometallic molecules
  • configuration-interaction-corrected Kohn-Sham theory for conical intersections
  • model-space diabatization of coupled electronic states for photochemistry
  • Franck-Condon models for line shapes in electronic spectroscopy
  • spectroscopy and photochemistry of thioanisole, including diabatic potential energy surfaces and coupled-surface molecular dynamics

Having completed his Ph. D. research, he now moves on to a position as software engineer with Google in Mountain View, California.

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