(6ct) QM-Based Multiscale Simulations for Applications in Electrocatalysis, Interfacial Chemistry, and Energetic Materials

There is an economic and environmental imperative to design and discover new materials. Computational science has become an essential partner to experiment for understanding the fundamental physical and chemical properties of materials. Recent dramatic developments in first-principles quantum mechanics (QM) methods have enabled accurate predictions for the properties of various systems. However, such QM methods are limited to several hundreds of atoms for dozens of picoseconds (ps) (10^−12 seconds). This capacity may grow by an order of magnitude over the next few years, but pure QM methods will remain far from meeting the requirement to inform the continuum degrees of freedom (e.g. solvent effect in electrochemical systems), which require millions of atoms (10⁶) and microseconds (10^−3 seconds) of simulations. Thus, there is an enormous gap between the scale of current QM methods and that of the real applications. My research is to develop and validate new computation tools and software for multiscale reactive simulations of materials and processes and then to apply these tools and methods to develop new generations of materials designed to have improved performance. My research is motivated toward a diverse set of applications. In particular, I am interested to apply these methods to electrochemical processes, catalytic reactions, interfacial chemistry, and materials under extreme conditions.

Postdoctoral Studies:

Advisor: Prof. William A. Goddard III, Caltech

Projects:

• Development of the quantum mechanics-based polarizable reactive force field (RexPoN) for multiscale simulations of materials and systems
• Development of polarizable charge equilibration (PQEq) model for predicting accurate electrostatic interactions in liquid, solids, and interfaces
• Prediction of structures and properties of green energetic materials from density functional theory (DFT) and reactive molecular dynamics

Co-authored Proposals:

• DOE, DE-SC0014607, funded (09/2015-09/2019)
• ONR, N00014-16-1-2059, funded (12/2015-11/2018)
• DARPA, 140D6319C0019, funded (3/2019-11/2019)

PhD Studies:

Advisors: Profs. Muhammad Sahimi and Theodore T. Tsotsis, University of Southern California

Dissertation: A process-based molecular model of silicon carbide (SiC) nano-porous membranes

Research Experience:

As a postdoctoral fellow, I developed the methodologies for constructing a very accurate reactive force field (FF), RexPoN, capable of describing complex reaction dynamics at the accuracy of ab initio CCSD QM (better than DFT). RexPoN retains high level QM accuracy for multiscale simulations of materials and energy systems with millions of atoms needed to make breakthroughs in the design of novel complex materials.

The application of RexPoN FF to water resulted in incredibly accurate properties of water (e.g. melting point to 0.2K accuracy). It showed that the lifetime of strong hydrogen bonds is ~ 90 femtoseconds at 298K, which was confirmed experimentally. In addition, it explained the puzzling hydrogen bonding network in water (a hundred years old problem) and the possible origin of anomalies in supercooled water.

To predict accurate electrostatic interactions in materials I developed the Polarizable Charge Equilibration (PQEq) method which uses atomic sized charges (not point charges) which are allowed to polarize every time step leading the accuracy of QM as dipoles are brought up to various molecules. I have validated the accuracy of PQEq for nearly all elements of periodic table including main groups and transition metals.

In addition, I have built on the accuracy for RexPoN to develop a new generation of hybrid computational framework, RexPoN embedded QM, or REQM, aimed at practical simulations on reactive systems with 100,000 to a million atoms while retaining the 0.05 eV accuracy of QM. In REQM the whole system (200,000 atoms for a 10 nm nanoparticle) is described with RexPoN, except for an embedded region of 200-300 atoms that uses QM to describe bond breaking processes. REQM can allow practical full solvent studies of electrocatalysis where QM is used only for atoms directly involved in bond breaking. This will extend full solvent studies to practical electrocatalysis on nanoparticles and nanowires. Also it will enable direct comparison to operando experiments for validation.

Future Plans:

I. New Generation of Catalysts for Electrochemical Water Splitting: Electrocatalytic water splitting driven by renewable energy input to produce clean H₂ is an essential component of the future energy portfolio. The challenge in developing dramatically improved catalysts is to develop deep understanding of the catalytic mechanisms. QM calculations of mechanism using explicit solvent have been validated by experiment, but the best electrocatalysts are nanoparticles and nanowires with 100,000 to millions of atoms. To make progress the QM accuracy has to be extended to such sizes.

REQM will enable this, allowing direct comparison to operando experiments and providing the means to use theory to guide the improvements in the catalyst. I propose to develop new generation of bifunctional nonprecious electrocatalysts to drive both HER and oxygen evolution reaction (OER) under the same conditions, useful for a wide pH range. My goal is to achieve at least one order of magnitude higher HER turnover frequency per catalyst site.

I anticipate funding from NSF (DMR, CBET, and CDS&E) and DOE. This work will be the focus of 50% of my efforts.

II. Thermodynamics and Adsorption Mechanism of Ions at Aqueous Interfaces: The adsorption and distribution of ions at the aqueous interfaces (solid and vapor) play a key role in the performance of many physical, chemical, atmospheric, and biological processes. The traditional view has ignored the presence of explicit ions at the liquid/vapor interface. However, recent experimental works using second order nonlinear optical techniques have proved that certain ions are enhanced at the interface.

Despite some theoretical efforts, clear understanding of the behavior of ions at the interface has remained challenging. I aim to change this situation. My group will utilize RexPoN FF and two-phase thermodynamics method (developed by Goddard group) to understand the thermodynamics and adsorption mechanism of the ions at the graphene/water interface due to its importance in many systems such as lithium-ion batteries and porous membranes for filtering, transistors, and supercapacitors. Our results will help experimentalist for effective engineering of the aqueous interface for potentially game-changing properties.

I anticipate funding from NSF (DMR, CBET, and CDS&E) and DOE. This work will be the focus of 30% of my efforts.

III. Structures, Properties, and Performance of Materials under Extreme Conditions: QM is providing increasingly accurate descriptions of materials under ordinary conditions of temperature and pressure. My interest is to extend these methods to the no-man’s region of extremely high temperature and pressure/stress gradients involving complex reaction kinetics, combustion, and explosions. I want to develop techniques to predict reliably the constitutive properties and reaction kinetics processes that control stability, performance, and sensitivity of high energy materials (EMs). I want to do this prior to synthesis and characterization and discover the best possible new EMs to help guide the experimentalists to focus only on the most promising systems. Short term challenge is to design insensitive EMs (due to risks in their use) without any loss in their performance. Long term is to describe combustion, chemical vapor deposition, and atomic layer deposition.

One goal is to utilize and validate RexPoN FF and REQM to develop a new generation of two-dimensional (2D) composite EMs with desirable insensitivity and much higher performance than the conventional EMs (e.g. HMX and RDX).

To ensure maximum impact, I will establish collaboration with the experimentalists. I anticipate funding from DoD, ONR, AFOSR, and perhaps from DOE. This work will be the focus of 20% of my efforts.

Teaching Interests:

I have experience teaching and mentoring students in the classroom and in the laboratory. As a teaching assistant I have given lectures and tutorial sessions in Transport Phenomena (i.e. Mass Transfer, Heat Transfer, and Viscous Flow), Reactor Design and Kinetics, and Advanced Engineering Mathematics. Also I have assisted in courses on molecular and materials simulations and quantum mechanics. During my postdoctoral studies I have mentored more than 10 postdocs, graduate, undergraduate, and high schools students for a variety of different projects. I am enthusiastic about the opportunity to teach undergraduate and graduate courses including Quantum Mechanics, Computer Simulation and Modeling, Transport Phenomena, Chemical Reaction Engineering, Engineering Thermodynamics, and Advanced Engineering Mathematics. I would like to offer at least one but possibly two courses related to multiscale atomistic simulations of materials and systems.

22 peer-reviewed publications (11 first author).

Selected Publications:

1. Naserifar and W. A. Goddard III, “Anomalies in Supercooled Water at ~230 K Arise from a 1D Polymer to 2D Network Topological Transformation”, Proceedings of the National Academy of Sciences (2019), Under Review
2. Naserifar, J. J. Oppenheim, H. Yang, T. Zhou, S. Zybin and W. A. Goddard III, “Development of Accurate Nonbond Potentials based on Periodic Quantum Mechanics Calculations for Molecular Simulations of Materials and Systems”, The Journal of Chemical Physics (2019), Under Review
3. Naserifar and W. A. Goddard III, “Liquid Water is a Dynamic Polydisperse Branched Polymer”, Proceedings of the National Academy of Sciences, 116 (6), 1998-2003 (2019)
4. Naserifar and W. A. Goddard III, “The Quantum Mechanics-based Polarizable Force Field for Water Simulations”, The Journal of Chemical Physics 149, 174502 (2018)
5. Naserifar, D. J. Brooks, W. A. Goddard III, and V. Cvicek, “Polarizable Charge Equilibration Model for Predicting Accurate Electrostatic Interactions in Molecules and Solids”, The Journal of Chemical Physics 146, 124117 (2017).
6. Naserifar, S. Zybin, C. Ye and William A. Goddard, III, “Prediction of Structures and Properties of 2,4,6-Triamino-1,3,5-Triazine-1,3,5-Trioxide (MTO) and 2,4,6-Trinitro-1,3,5-Triazine-1,3,5-Trioxide (MTO3N) Green Energetic Materials from DFT and ReaxFF Molecular Modeling”, Journal of Materials Chemistry A 4, 1264-1276 (2016)
7. Naserifar, W. A. Goddard, III, M. Sahimi and T. T. Tsotsis, “First Principles-based Multiparadigm, Multiscale Strategy for Simulating Complex Materials Processes with Applications to Amorphous SiC Films”, The Journal of Chemical Physics 142, 174703 (2015)
8. Naserifar, T. T. Tsotsis, W. A. Goddard, III, and M. Sahimi, “Toward a Process-based Molecular Model of SiC Membranes: III. Prediction of Transport and Separation of Binary Gaseous Mixtures based on the Atomistic Reactive Force Field”, Journal of Membrane Science 473, 85-93 (2015)
9. Jaramillo-Botero, S. Naserifar, and W. A. Goddard, III, “A General Multi-objective Force Field Optimization Framework and its Application to the Design of Reactive Force Fields for Silicon Carbide”, Journal of Chemical Theory and Computation 10, 1426–1439 (2014)
10. Naserifar, L. Liu, W. A. Goddard, III, T. T. Tsotsis, and M. Sahimi, “Toward a Process-Based Molecular Model of SiC Membranes. I. Development of a Reactive Force Field”, The Journal of Physical Chemistry C 117, 3308–3319 (2013)
11. Naserifar, W. A. Goddard, III, L. Liu, T. T. Tsotsis, and M. Sahimi, “Toward a Process-Based Molecular Model of SiC Membranes. II. Reactive Dynamics Simulation of the Pyrolysis of Polymer Precursor to Form Amorphous SiC”, The Journal of Physical Chemistry C 117, 3320–3332 (2013)