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Gap Engineering and Simulation of Advanced Materials

Prasai, Kiran
http://orcid.org/0000-0001-6552-097X
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1503393620371266

Abstract Details

2017, Doctor of Philosophy (PhD), Ohio University, Physics and Astronomy (Arts and Sciences).
Generating computer models of materials that faithfully represent all of our current state of knowledge about those materials has remained an unsolved problem. In particular, models of amorphous solids following from a molecular dynamics (MD) simulation commonly show structural defects and related mid-gap electronic states that are not present in the real materials. In this dissertation, we present a novel way of using a priori knowledge of the electronic band gap of amorphous systems to guide MD simulations. This involves computing Hellmann-Feynman forces associated with certain electronic states and judiciously coupling them to the total force in MD simulations. We show that such a method can provide a means to purge structural defects. By producing a series of models of amorphous carbon with varying sp2/sp3 ratio, we’ll show that this method offers useful new flexibility in modeling. And, we demonstrate, for the first time, how MD simulations can be biased to systematically model an insulator-metal transition in glassy systems. The nature of electron transport in eSe3Ag glass is explored using advanced methods and important inferences are drawn about the role of Ag atoms in electronic conductivity. In particular, it is shown that a certain Se-Ag phase in this glass plays a dominant role in electron transport. We also investigate the response of a-GeSe3Ag to radiation damage using empirical interatomic interactions and show that the glass exhibits rapid recovery after a knock on event. Finally, we consider the the coupling between lattice vibrations and electronic states in disordered systems and show that disorder induced localization of states dictates the thermal modulation of electronic energy.
David A. Drabold (Advisor)
Sumit Sharma (Committee Member)
Eric Stinaff (Committee Member)
Gang Chen (Committee Member)
124 p.
Condensed Matter Physics; Physics
gap engineering; simulations; chalcogenides; amorphous silicon; molecular dynamics; modeling; CBRAM; amorphous carbon; insulator-metal transition; materials design

Recommended Citations

Citations

  • Prasai, K. (2017). Gap Engineering and Simulation of Advanced Materials [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1503393620371266

    APA Style (7th edition)

  • Prasai, Kiran. Gap Engineering and Simulation of Advanced Materials. 2017. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1503393620371266.

    MLA Style (8th edition)

  • Prasai, Kiran. "Gap Engineering and Simulation of Advanced Materials." Doctoral dissertation, Ohio University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1503393620371266

    Chicago Manual of Style (17th edition)

ohiou1503393620371266
189
© 2017, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.