Quantum chemistry

Giannis Mpourmpakis and His Colleagues Revealed the Mystery Behind Formation of Metal Nano-particles at Specific Sizes

  • By Burcu Ozden
  • 30 August 2017

Nature Communications, co-authored by Giannis Mpourmpakis, and PhD candidate Michael Taylor, offers a possible way to unravel these mysteries, with the help of computer simulations. “In applying our new theory, we aim to accelerate discovery and application,” said Mpourmpakis. From molecular carriers for targeted drug delivery to systems for energy generation and storage to solar cells, this research could help.

 

 

Computational Study of Ni-Catalyzed C−H Functionalization: Factors That Control the Competition of Oxidative Addition and Radical Pathways

  • By Aude Marjolin
  • 2 August 2017

To guide the development of a more diverse set of Ni-catalyzed C−H bond functionalizations, a thorough understanding of the mechanisms, reactivity, and selectivity of these reactions is required. Peng Liu and his student Humair Omer have undertaken a computational study of the functionalization of the C−H bonds in molecules that contain the N,N-bidentate directing group with Ni catalyst and various coupling  partners, e.g. phenyl iodide (Ph−I), which has been published in the July 26, 2017 issue of the Journal of the American Chemical Society.

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. "Role of anisotropy in determining stability of electrodeposition at solid-solid interfaces", Zeeshan Ahmad and Venkatasubramanian ViswanathanPhys. Rev. Materials 1, 055403 (2017)
  2. "Evaluating the Potential of Platooning in Lowering the Required Performance Metrics of Li-Ion Batteries to Enable Practical Electric Semi-Trucks", M. Guttenberg, S. Sripad, V. Viswanathan ACS Energy Lett.  2, 2642 (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 Viswanathan, Joule 1, 1 (2017)
  4. "Maximal predictability approach for identifying the right descriptors for electrocatalytic reactions," Dilip Krishnamurthya, Vaidish Sumariab, Venkatasubramanian Viswanathan arXiv:1709.02875v2
  5. "Anisotropy in Stability of Electrodeposition at Solid-Solid Interfaces and Implications for Metal Anodes," Zeeshan Ahmad, Venkatasubramanian Viswanathan, arXiv:1707.00064v2
Phone: 
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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