Don Nicholson came to our department after retiring from Oak Ridge National Laboratory (ORNL) in 2014 where was a computational materials scientist. While at ORNL he developed methods that describe from first principles the properties of metals. His approach uses the most powerful computers in the world to solve the quantum mechanical equations that determine how electrons bond metals together and how electrons flow through metals. For this work he received three Gordon Bell Prizes, a Department of Energy Outstanding Research Award, and was named a Smithsonian Laureate. He joined the Physics Department to continue his work on the fundamental description of materials.
Ph.D. in Theoretical Condensed Matter Physics, Brandeis University (1982)
- Multiple Scattering Theory: This theory describes the behavior of electrons in a metal on the basis of how an electron scatters from single isolated potentials that represent each of the atoms in the material. It is the most local treatment of the electron problem and therefore the best suited to solution on large-scale parallel computers. It is also a very challenging theory that requires complex implementation.
- Advance Statistical Methods: Systems naturally move toward lower energy and more disorder. They move toward disorder because the number of disordered states is large compared to ordered states. The measure of disorder is the entropy. The importance of disorder increases with temperature. At a phase transition, for example melting of a solid, the entropy and energy are of equal significance. Advanced statistical methods are needed to approximately count the number of states with a given energy in order to determine the entropy so that together the energy and entropy can be used to explain phase transition.
- Density Functional Theory of Electrons: This theory is the basis of the modern description of materials. It uses solutions of the Schrodinger or Dirac equations for single electrons moving in an effective potential chosen to approximate the energy of the interacting electron system. This approach has been very successful, however, significant practical limitations and fundamental questions remain. He is working on an approach that focuses on the pair correlation in the electron fluid.
- Classical Density Functional Theory: He is extending Classical Density Functional Theory to discover simple relationships between the entropy and pair correlation. The needed input, pair correlation my come from either experiment or simulation.
- Magnetic properties of Metals: He is interested in the influence of electron spin on the dynamics and thermodynamics of magnetic materials. The effect of very large magnetic fields on materials is particularly interesting and underexplored.
- Combined molecular and spin dynamics in magnetic materials: He is working on computer codes that moves the atoms based on Newton’s equations of motion and rotates the orientation of atomic level magnetic moments according to the Landau-Lifshitz equation. This work is important for understanding the properties of bulk materials and spintronics.
- Metallic Glasses: When most liquid metal alloys are cooled they crystalize; metallic glasses are those that don’t crystallize but instead become a frozen liquid, i.e., a glass. The atomic dynamics near the glass transition is poorly understood. I use a variety of tools to study this regime.
- Atomic Level Stress: In materials near zero temperature the forces on all atoms are zero; we know this because they are not accelerating. However, stresses at the atomic level can be very large. He is developing first principles approaches to the atomic level stress in hopes that this stress can be correlated with and help explain measured and simulated behavior.
- Defects in metals: When a material is subjected to forces, radiation, or chemical attack, it is the defects that redistribute energy and stress. The defects determine whether or not a material fails. He is using large scale computing to study the properties of defects in metals.
- Magneto Caloric Effect: When some materials are moved into a magnetic field they become hotter. This effect can be used to pump heat out of a building, i.e., air-conditioning. Magnetic based cooling has the potential to outperform conventional air-conditioning that is based on compressing a gas to make it hotter. He is using first principles techniques to study these metals.
- Madhusudan Ojha, Don M. Nicholson, and Takeshi Egami, “Ab-initio atomic level stresses in Cu-Zr systems,” Bulletin of the American Physical Society, 2014.
- Dilina Perera, David P. Landau, Don M. Nicholson, Malcolm G. Stocks, Markus Eisenbach, Junqi Yin, and Gregory Brown, “Combined molecular dynamics-spin dynamics simulations of bcc iron,” Journal of Physics: Conference Series, 2014.
- A. Gonis, X-G Zhang, D.M. Nicholson, and G.M. Stocks, “Energy convexity as a consequence of decoherence and pair-extensive interactions in many-electron systems,” Journal of Physics and Chemistry of Solids, 2014.
- Markus Eisenbach, Gregory Brown, and Don M. Nicholson, “Exact enumeration of an Ising model for Ni2MnGa,” Bulletin of the American Physical Society, 2014.
- G. Brown, P.A. Rikvold, D.M. Nicholson, Kh. Odbadrakh, J-Q Yin, M. Eisenbach, and S. Miyashita, “Flat-histogram Monte Carlo in the Classical Antiferromagnetic Ising Model,” Bulletin of the American Physical Society, 2014.
- Aftab Alam, Suffian N. Khan, Andrei Smirnov, D.M. Nicholson, and Duane D. Johnson, “Green's function multiple-scattering theory with a truncated basis set: An Augmented-KKR formalism,” arXiv preprint arXiv (1407.6791), 2014.
- Khorgolkhuu Odbadrakh, Nichiolas William McNutt, Donald M. Nicholson, Orlando Rios, and David J. Keffer, “Lithium diffusion at Si-C interfaces in silicon-graphene composites,” Applied Physics Letters, 2014.
- Khorgolkhuu Odbadrakh, Don Nicholson, Markus Eisenbach, Gregory Brown, and Aurelian Rusanu, “Magnetic entropy change calculated from first principles based statistical sampling technique: Ni2MnGa,” Bulletin of the American Physical Society, 2014.
- Don Nicholson, Kh. Odbadrakh, G.D. Samolyuk, R.E. Stoller, X.G. Zhang, and G.M. Stocks, “Million atom DFT calculations using coarse graining and petascale computing,” Bulletin of the American Physical Society, 2014.
- Don M. Nicholson, Kh. Odbadrakh, B.A. Shassere, O. Rios, J. Hodges, G.M. Ludtka, W.D. Porter, A.S. Sefat, A. Rusanu, and G. Brown, “Modeling and characterization of the magnetocaloric effect in Ni2MnGa materials,” International Journal of Refrigeration, 2014.
- M. Däne, A. Gonis, D.M. Nicholson, and G.M. Stocks, “On a solution of the self-interaction problem in kohn-sham density functional theory,” Journal of Physics and Chemistry of Solids, 2014.
- Dilina Perera, David P. Landau, Don M. Nicholson, G. Malcolm Stocks, Markus Eisenbach, Junqi Yin, and Gregory Brown, “Phonon-magnon interactions in body centered cubic iron: A combined molecular and spin dynamics study,” Journal of Applied Physics, 2014.
- A. Gonis, X-G Zhang, D.M. Nicholson, and G.M. Stocks, “Self-entanglement and the dissociation of homonuclear diatomic molecules,” Molecular Physics, 2014.
- Yuri Osetsky, Odbadrakh Khorgolkhuu, German Samolyuk, Don Nicholson, Roger Stoller, and Malcolm Stocks, “The interaction of Cr and Ni solute atoms with core of screw and edge dislocation in bcc Fe,” Bulletin of the American Physical Society, 2014.