PAN 319 (office), 624-2386
ganzx001 @ umn.edu • curriculum vitae
I'm a solid-state physicist with interests in computational studies of materials. Currently I am studying new classes of porous materials called metal organic frameworks, as well as two-dimensional materials.
Member of Minnesota Supercomputing Institute
I am interested in modeling the properties of novel materials. This can include 2 dimensional materials, as well as porous frameworks materials such as metal organic frameworks and covalent organic framework materials. These new porous materials are built from molecular building blocks, and so can be designed to provide a very wide range of capabilities.
The Initial Stages of Melting of Graphene Between 4000 K and 6000 K
Graphene and its analogues have some of the highest predicted melting points of any materials. Previous work estimated the melting temperature for freestanding graphene to be a remarkable 4510 K. However, this work relied on theoretical methods that do not accurately account for the role of bond breaking or complex bonding configurations in the melting process. Furthermore, experiments to verify these high melting points have been challenging. Practical applications of graphene and carbon nanotubes at high temperatures will require a detailed understanding of the behavior of these materials under these conditions. Therefore, we have used reliable ab initio molecular dynamics calculations to study the initial stages of melting of freestanding graphene monolayers between 4000 and 6000 K. To accommodate large defects, and for improved accuracy, we used a large 10 × 10 periodic unit cell. We find that the system can be heated up to 4500 K for 18 ps without melting, and 3-rings and short lived broken bonds (10-rings) are observed. At 4500 K, the system appears to be in a quasi-2D liquid state. At 5000 K, the system is starting to melt. During the 20 ps simulation, diffusion events are observed, leading to the creation of a 5775 defect. We calculate accurate excitation energies for these configurations, and the pair correlation function is presented. The modified Lindemann criterion was calculated. Graphene and nanotubes together with other proposed high melting point materials would be interesting candidates for experimental tests of melting in the weightless environment of space.
Computational Study of Quasi-2D Liquid State in Free Standing Platinum, Silver, Gold, and Copper Monolayers
LM Yang, AB Ganz, M Dornfeld, E Ganz
Condensed Matter 1 (1), 1
We also recently released a study on the freestanding 2-D silver monolayer.
1. Mussels have a remarkable ability to bond to solid surfaces under water. From a microscopic perspective, the first step of this process is the adsorption of dopa molecules to the solid surface. In fact, it is the catechol part of the dopa molecule that is interacting with the surface. These molecules are able to make reversible bonds to a wide range of materials, even underwater. We uncover the nature of this competitive absorption by atomic scale modeling of water and catechol adsorbed at the geminal (001) silica surface using density functional theory calculations. We find that catechol molecules displace preadsorbed water molecules and bond directly on the silica surface. Using molecular dynamics simulations, we observe this process in detail. We also calculate the interaction force as a function of distance, and observe a maximum of 0.5 nN of attraction. The catechol has a binding energy of 23 kcal/mol onto the silica surface with adsorbed water molecules. Here is the link to the press release for this paper: External Link
Energetics and thermodynamics of the initial stages of hydrogen storage by spillover on prototypical Metal-Organic Framework (MOF) and Covalent-Organic Framework (COF) materials. For many years, experimenters have struggled to reproduce and extend the original spillover results that were carried out on IRMOF-1. For pure IRMOF-1 it has been suggested (based on calculations of molecular fragments) that there is an enthalpy barrier to the addition of the first hydrogen per benzene, and that this barrier is removed by hole doping. This explains why very specific procedures such as annealing cycles (which damage the frameworks) needed to be used in the experiments. Using density functional theory on more accurate and much more computationally expensive periodic frameworks, we do not observe this enthalpy barrier. However, we do observe that the binding energy for the first hydrogen is unfavorable and creates a kinetic barrier without hole doping. Hole doping by zinc vacancies removes this energy barrier. Therefore, hole doping by Zn vacancies or other means is still necessary for the hydrogen storage process to proceed. We also see that the direction of the hydrogen sorption reaction as a function of hydrogen gas pressure can be predicted by the change in Gibbs free energy.
Another challenge for the use of for the use of IRMOF-1 in real-world hydrogen storage situations is that the material degrades upon exposure to small amounts of water vapor. Therefore more durable materials such as water resistant metal organic frameworks, or covalent organic frameworks would be much more desirable for these applications. Unfortunately, as mentioned above, it has not been possible to achieve significant hydrogen storage in either of these cases. Now, our calculations may explain why it has been difficult to achieve significant hydrogen spillover on COF materials. For COF-5, we find that the energy barrier is not resolved by doping, and therefore hydrogen spillover will not proceed unless some new sample preparation technique is developed.
Eric Ganz, Ariel B. Ganz, Li-Ming Yang and Matthew Dornfeld , The initial stages of melting of graphene between 4000 K and 6000 K, Phys. Chem. Chem. Phys. [abstract]
Li-Ming Yang, Ariel B. Ganz, Matthew Dornfeld and Eric Ganz, Computational Study of Quasi-2D Liquid State in Free Standing Platinum, Silver, Gold, and Copper Monolayers, Condensed Matter [abstract] [download condensedmatter-01-00001(1).pdf]
Li-Ming Yang, Eric Ganz, Zhongfang Chen, Zhi-Xiang Wang and Paul von Ragué Schleyer, Four Decades of the Chemistry of Planar Hypercoordinate Compounds, Angewandte Chemie International Edition [abstract]
Yang L, Yang V, Popov I A, Boldyrev A I, Heine T, Frauenheim T, Ganz E., Two-Dimensional Cu2Si Monolayer with Planar Hexacoordinate Copper and Silicon Bonding, Journal of the American Chemical Society [abstract]
Shabeer Ahmad Mian, Li-Ming Yang, Leton Chandra Saha, Ejaz Ahmed, Ajmal Muhammad, Eric Ganz, A Fundamental Understanding of Catechol and Water Adsorption on a Hydrophilic Silica Surface: Exploring the Underwater Adhesion Mechanism of Mussels on an Atomic Scale, Langmuir [abstract]
Li-Ming Yang, Eric D Ganz, Stian Svelle and Mats Tilset , Computational Exploration of Newly Synthesized Zirconium Metal-Organic Frameworks UiO-66, 67, 68 and Analogues, J. Mater. Chem. C [abstract]
L.-M. Yang, G.-Y. Fang, J. Ma, E. Ganz, and S.S. Han, Band Gap Engineering of MOF-5 by Atom Substitution, J. Mol. Chem. C
E. Ganz* and M. Dornfeld, Energetics and Thermodynamics of the Initial Stages of Hydrogen Storage by Spillover on Prototypical Metal-Organic Framework and Covalent-Organic Framework Materials, J. Phys. Chem. C [abstract]
Eric Ganz and Matthew Dornfeld, Storage Capacity of Metal-Organic and Covalent-Organic Frameworks by Hydrogen Spillover, J. Phys. Chem. C. 116, 3661 [abstract] [download jp2106154.pdf]
Mayur Suri, Matthew Dornfeld, and Eric Ganz, Calculation of hydrogen storage capacity of metal-organic and covalentorganic frameworks by spillover, [abstract] [download JCPSA613117174703_1.pdf]
T. Sagara and E. Ganz, “Calculations of Dihydrogen Binding to Doped Carbon Nanostructures”, J. Phys. Chem. C. (2008)
T. Sagara, J. Ortony, and E. Ganz, New isoreticular metal-organic framework materials for high hydrogen storage capacity, Journal of Chemical Physics [abstract] [download C:\Users\Eric\Documents\Papers\Ganz\New isoreticular metal-o]