Quantum chemistry

Novel Theory Developed by Giannis Mpourmpakis Explains How Metal Nanoparticles Form

  • By Aude Marjolin
  • 12 July 2017

Although scientists have for decades been able to synthesize nanoparticles in the lab, the process is mostly trial and error, and how the formation actually takes place is obscure. However, a study recently published in Nature Communications entitled "“Thermodynamic Stability of Ligand-Protected Metal Nanoclusters” by Giannis Mpourmpakis and PhD candidate Michael G. Taylor explains how metal nanoparticles form. The research, completed in Mpourmpakis’ Computer-Aided Nano and Energy Lab (C.A.N.E.LA.), is funded through a National Science Foundation CAREER award and bridges previous research focused on designing nanoparticles for catalytic applications.

John Keith Among RSC Emerging Investigators in 2017

  • By Aude Marjolin
  • 14 June 2017

John Keith was among the Emerging Investigators in 2017 recommended by experts in the field of materials chemistry research in a themed issue of the Journal of Materials Chemistry A, published by the Royal Society of Chemistry. His article “Computational investigation of CO2 electroreduction on tin oxide and predictions of Ti, V, Nb and Zr dopants for improved catalysis” published in the issue outlines the work of Keith and his team on improving the performance of tin electrocatalysts for CO2 reduction.

In Silico Searches for Efficient Renewable Energy Catalysts Through Chemical Compound Space

Speaker(s): 
John Keith
Dates: 
Friday, February 3, 2017 - 11:30am to 12:30pm

This talk will provide an overview of our group’s work using both standard and atypical high-performance computational chemistry modeling to elucidate atomic scale reaction mechanisms of catalytic reactions. I will introduce our toolkit of in silico methods for accurately modeling solvating environments and realistic nanoscale architectures. I will then present how these methods can be used for predictive insights into chemical and material design. The talk will then summarize our progress in unraveling reaction mechanisms for 1) electrochemical CO2 reduction with...

Peng Liu Receives NSF CAREER Award

  • By Aude Marjolin
  • 16 December 2016

Peng Liu has been selected to receive a National Science Foundation CAREER award based upon his proposal, entitled "Computational Studies of Transition-Metal-Catalyzed Reactions in Organic Synthesis." 

In this CAREER project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Peng Liu of the Department of Chemistry at the University of Pittsburgh is developing new strategies to use computational tools to investigate mechanisms and effects of ancillary ligands in transition-metal-catalyzed reactions of unactivated starting materials, such as C-C and C-H bonds, and unactivated olefins. The goal of this research is to reveal the fundamental reactivity rules of common organometallic intermediates in these transformations and to develop new models to interpret ligand effects on reactivity and selectivity. This proposal’s educational and outreach plan aims to maximize the power of computations to enhance learning of organic chemistry concepts and to facilitate synthetic organic chemistry research. Professor Liu’s team will develop virtual reality (VR) software and educational materials to visualize three-dimensional molecular structures and reaction mechanism videos in an interactive and immersive environment.

Snapshots of Proton Conduction Process in Water

  • By Aude Marjolin
  • 5 December 2016

Scientists Capture Snapshots of the Proton Conduction Process in Water

The motion of protons (positively charged H atoms) in water is associated with water’s conduction of electricity and is involved in many important processes including vision, signaling in biological systems, photosynthesis and, the operation of fuel cells. Both artificial photosynthetic systems and fuel cells are of growing interest for clean energy technologies. However, the details of how protons move in water have remained elusive, and an enhanced understanding of the nature of this process is needed to improve the technologies that depend on proton transfer.

An international team of scientists, including a University of Pittsburgh professor and graduate student, has used spectroscopic methods to obtain snapshots of the process by which a proton is relayed from one water molecule to the next. The research is published in a paper in the December 2, 2016 issue of the journal Science.

Structure and Reactivity of Functional Molecules on Surfaces

Speaker(s): 
Reinhard J. Maurer
Dates: 
Thursday, February 9, 2017 - 4:00pm to 5:00pm

Fundamental understanding of molecular structure and chemical reactivity at complex interfaces is key to many technological applications ranging from single molecule electronics to functional surfaces. An important goal of molecular nanotechnology is to manipulate single molecules in well-defined chemical environments. Using electronic structure methods, we study prototypical example systems such as azobenzene [1] and porphyrine [2] derivatives adsorbed on well-defined single crystal metal surfaces. Hereby the focus lies on the effects of molecule functionalization,...

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Websites: 
Personal | Department
Department of Mechanical Engineering, Carnegie Mellon University
Ph.D., Mechanical Engineering, Stanford University, 2013
Summary:

Venkat Viswanathan's research focus is on identifying the scientific principles governing material design, inorganic, organic and biomaterials, for novel energy conversion and storage routes. The material design is carried out through a suite of computational methods being developed in the group validated by experiments.  Some key research thrusts include identifying principles of electrolytes design (organic material) that can tune electrode catalysis, identification of new anode, cathode (inorganic materials) and electrolyte materials for next generation batteries, new electrocatalysts (inorganic) and biomaterials for energy storage and separation applications. In addition to material design, our group is involved in several cross-cutting areas such as battery controls, electric vehicle security and GPU accelerated computing.

Research interests:

  • Computational material design
  • Density functional theory simulations
  • Phase-field modeling
  • Next generation batteries, fuel cells
  • Electrocatalysis for energy conversion and storage
  • Data-driven material discovery
  • Bio-inspired and bio-mimetic materials
  • Controls for energy systems
  • GPU accelerated computing
Most Cited Publications: 
  1. "Twin Problems of Interfacial Carbonate Formation in Nonaqueous Li–O2 Batteries," B. D. McCloskey, A. Speidel, R. Scheffler, D. C. Miller, V. Viswanathan, J. S. Hummelshøj, J. K. Nørskov, and A. C. Luntz, J. Phys. Chem. Lett. 3, 997 (2012)
  2. "Electrical conductivity in Li2O2 and its role in determining capacity limitations in non-aqueous Li-O2 batteries," V. Viswanathan, K. S. Thygesen, J. S. Hummelshøj, J. K. Nørskov, G. Girishkumar, B. D. McCloskey and A. C. Luntz, J. Chem. Phys. 135, 214704 (2011)
  3. "Solvating additives drive solution-mediated electrochemistry and enhance toroid growth in non-aqueous Li–O2 batteries" Nagaphani B. Aetukuri, Bryan D. McCloskey, Jeannette M. García, Leslie E. Krupp, Venkatasubramanian Viswanathan & Alan C. Luntz, Nature Chemistry 7, 50 (2015)
  4. "Universality in Oxygen Reduction Electrocatalysis on Metal Surfaces," Venkatasubramanian Viswanathan, Heine Anton Hansen, Jan Rossmeisl, and Jens K. Nørskov, ACS Catal. 2, 1654 (2012)
  5. "Direct observation of the oxygenated species during oxygen reduction on a platinum fuel cell cathode," Hernan Sanchez Casalongue, Sarp Kaya, Venkatasubramanian Viswanathan, Daniel J. Miller, Daniel Friebel, Heine A. Hansen, Jens K. Nørskov, Anders Nilsson & Hirohito Ogasawara, Nature Communications 4, 2817 (2013)
Recent Publications: 
  1. "Anisotropy in stability of electrodeposition at solid-solid interfaces and implications for metal anodes," Zeeshan Ahmad, Venkatasubramanian ViswanathanarXiv:1707.00064
  2. "Performance Metrics Required of Next-Generation Batteries to Make a Practical Electric Semi Truck," Shashank Sripad and Venkatasubramanian ViswanathanACS Energy Lett. 2, 1669 (2017)
  3. "Surface Restructuring of Nickel Sulfide Generates Optimally-Coordinated Active Sites for ORR Catalysis," Bing Yan, Dilip Krishnamurthy, Christopher H. Hendon, Siddharth Deshpande, Yogesh Surendranath, Venkatasubramanian ViswanathanarXiv:1706.04090
  4. "Quantifying Confidence in Density Functional Theory Predicted Magnetic Ground States," Gregory Houchins, Venkatasubramanian ViswanathanarXiv:1706.00416
  5. "Effect of Dynamic Surface Polarization on the Oxidative Stability of Solvents in Nonaqueous Li-O2 Batteries," Abhishek Khetan, Heinz Pitsch, Venkatasubramanian ViswanathanarXiv:1705.03862
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Websites: 
Personal | Department
Department of Physics and Astronomy, University of Pittsburgh
Ph.D. Physics, University of Science & Technology of China, 2003
Summary:

1. The wet electron structure of the H/H2O/TiO2(110) surfaces system using Density Functional Theory.

2. The excited state structure of H/H2O/TiO2(110) using delta-scf method and TDDFT.

3. The resonance of alkali atoms adsorbed on Ag and Cu surface using first-principle and model potential calculation methods.

Selected Publications: 
  • "Time-resolved photoemission study of the electronic structure and dynamics of chemisorbed alkali atoms on Ru(0001)," Shengmin Zhang, Cong Wang, Xuefeng Cui, Yanan Wang, Adam Argondizzo, Jin Zhao and Hrvoje Petek, Phys. Rev. B 93, 045401 (2016)
  • "Temperature- and Coverage-Dependent Kinetics of Photocatalytic Reaction of Methanol on TiO2(110)-(1x1) Surface," Hao Feng, Shijing Tan, Haoqi Tang, Qijing Zheng, Yongliang Shi, Xuefeng Cui, Xiang Shao, Aidi Zhao, Jin Zhao, and Bing Wang, J. Phys. Chem. C, 120, 5503 (2016)
  • "Nano-scale Polar-Nonpolar Oxide Heterostructures for Photocatalysis," Hongli Guo, Wissam A. Saidi, Jinlong Yang and Jin Zhao, Nanoscale 8, 6057 (2016)

Quantum Mechanics, Chemical Space, and Machine Learning

Speaker(s): 
O. Anatole von Lilienfeld
Dates: 
Thursday, September 29, 2016 - 4:30pm to 5:30pm

Many of the most relevant chemical properties of matter depend explicitly on atomistic details, rendering a first principles approach mandatory. Alas, even when using high-performance computers, brute force high throughput screening of compounds is beyond any capacity for all but the simplest systems and properties due to the combinatorial nature of chemical space, i.e. all compositional, constitutional, and conformational isomers. Consequently, efficient exploration algorithms need to exploit all implicit redundancies present in chemical space. I will discuss...

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Personal | Department
Department of Materials Science and Engineering, Carnegie Mellon University
Ph.D., Chemistry, Weizmann Institute of Science, 2010
Summary:

Computational Materials Science

The goal of our research is to computationally design materials with desired properties for target applications.

Through the portal of computer simulations we gain access to the vast configuration space of materials structure and composition. We can explore the uncharted territories of materials that have not been synthesized yet and predict their properties from first principles, based solely on the knowledge of their elemental composition and the laws of quantum mechanics.

To navigate the configuration space we use genetic algorithms, steered to the most promising regions by the evolutionary principle of survival of the fittest. We develop a massively parallel genetic algorithm code, GAtor, and run it on some of the world’s most powerful supercomputers. We apply our methods to study functional nano-structured interfaces in organic and hybrid solar cells, molecular crystals, layered materials, and cluster-based nanocatalysts.

Most Cited Publications: 
  1. "Dispersion Interactions with Density-Functional Theory: Benchmarking Semiempirical and Interatomic Pairwise Corrected Density Functionals," Noa Marom, Alexandre Tkatchenko, Mariana Rossi, Vivekanand V. Gobre, Oded Hod, Matthias Scheffler, and Leeor Kronik, J. Chem. Theory Comput. 7, 3944 (2011)
  2. "Stacking and Registry Effects in Layered Materials: The Case of Hexagonal Boron Nitride," Noa Marom, Jonathan Bernstein, Jonathan Garel, Alexandre Tkatchenko, Ernesto Joselevich, Leeor Kronik, and Oded Hod, Phys. Rev. Lett. 105, 046801 (2010)
  3. "Electronic structure of copper phthalocyanine: A comparative density functional theory study," Noa Marom, Oded Hod, Gustavo E. Scuseria, and Leeor Kronik, J. Chem. Phys. 128, 164107 (2008)
  4. "Describing Both Dispersion Interactions and Electronic Structure Using Density Functional Theory: The Case of Metal−Phthalocyanine Dimers," Noa Marom, Alexandre Tkatchenko, Matthias Scheffler and Leeor Kronik, J. Chem. Theory Comput. 6, 81 (2010)
  5. "Density functional theory of transition metal phthalocyanines, I: electronic structure of NiPc and CoPc—self-interaction effect," Noa Marom, Leeor Kronik, Appl. Phys. A 95, 159 (2009)
Recent Publications: 
  1. "Effect of packing motifs on the energy ranking and electronic properties of putative crystal structures of tricyano-1,4-dithiino[c]-isothiazole," F. Curtis, X. Wang and N. MaromActa Cryst. B72, 562 (2016)
  2. "Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules IV: Electron-Propagator Methods," O. Dolgounitcheva, Manuel Díaz-Tinoco, V. G. Zakrzewski, Ryan M. Richard, Noa Marom, C. David Sherrill, and J. V. Ortiz J. Chem. Theory Comput. 12, 627 (2016)
  3. "Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules III: A Benchmark of GW Methods," Joseph W. Knight, Xiaopeng Wang, Lukas Gallandi, Olga Dolgounitcheva, Xinguo Ren, J. Vincent Ortiz, Patrick Rinke, Thomas Körzdörfer, and Noa MaromJ. Chem. Theory Comput. 12, 615 (2016)
  4. "Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules II: Non-Empirically Tuned Long-Range Corrected Hybrid Functionals," Lukas Gallandi, Noa Marom, Patrick Rinke, and Thomas Körzdörfer, J. Chem. Theory Comput. 12, 605 (2016)
  5. "Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules I. Reference Data at the CCSD(T) Complete Basis Set Limit," Ryan M. Richard, Michael S. Marshall, O. Dolgounitcheva, J. V. Ortiz, Jean-Luc Brédas, Noa Marom, and C. David Sherrill, J. Chem. Theory Comput. 12, 595 (2016)

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