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Density-Functional Theory Study of Materials and Their Properties at Non-Zero Temperature

Antolin, Nikolas
http://rave.ohiolink.edu/etdc/view?acc_num=osu1452253704

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
Density functional theory (DFT) has proven useful in providing energetic and structural data to inform higher levels of simulation as well as populate materials databases. However, DFT does not intrinsically include temperature effects that are critical to determining materials behavior in real-world applications. By considering the magnitude of critical energy differences in a system to be studied, one may select the appropriate level of additional theory with which to supplement DFT to obtain meaningful results with respect to temperature-induced behavior. This thesis details studies on three materials systems, representing three distinct levels of additional theory used in the study of thermally-induced behavior. After introducing the concepts involved in extracting thermal data from atomistics and density functional theory in chapters 1 and 2, chapter 3 details studies on a Ni-base superalloy system and its behavior in creep testing at high temperature due to planar defects. Chapters 4 and 5 detail work on thermal stabilization of BCC phases which are unstable without temperature effects and the progress in calculating the thermodynamic stability of vacancies in these and other BCC systems. Chapter 6 describes a study of thermal effects coupling to magnetism in indium antimonide (InSb), which are the result of previously unobserved coupling between phonons and magnetic field in a diamagnetic material. All three of the systems studied exhibit materials properties which are strongly temperature-dependent, but the level of theory necessary to study them varies from simple ground state calculations to consideration of the effects of single vibrational modes within the material. Since many of the approaches used and introduced here are computationally intensive and push the limits of publicly available computational resources, this thesis puts additional focus on optimizing code execution and choosing an appropriate level of theory to probe a given material system. An inappropriate level of theory can either be computationally wasteful (or unfeasible) or yield meaningless results; it is only by the inclusion of appropriate thermal effects, determined by system to be considered, that valid results can be obtained. Though much progress has been made in generalizing the approaches described in this thesis, further research will be necessary if we hope to fulfill the lofty goal of a universally applicable method of extracting thermal data from first principles in a way that guarantees valid and useful results.
Wolfgang Windl (Advisor)
Maryam Ghazisaeidi (Committee Member)
J.-C. Zhao (Committee Member)
Robert de Jong (Committee Member)
217 p.
Materials Science
phonons, entropy, lattice dynamics, thermal properties

Recommended Citations

Citations

  • Antolin, N. (2016). Density-Functional Theory Study of Materials and Their Properties at Non-Zero Temperature [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1452253704

    APA Style (7th edition)

  • Antolin, Nikolas. Density-Functional Theory Study of Materials and Their Properties at Non-Zero Temperature. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1452253704.

    MLA Style (8th edition)

  • Antolin, Nikolas. "Density-Functional Theory Study of Materials and Their Properties at Non-Zero Temperature." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1452253704

    Chicago Manual of Style (17th edition)

osu1452253704
782
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This open access ETD is published by The Ohio State University and OhioLINK.