Chemistry Department Seminar, Featuring Prof. Yong-Hoo Kim, (KAIST) from Daejeon, Korea "Electrified Electrochemical Interfaces from a Quantum Transport Viewpoint"
April 21,
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Seminar hosted by Prof. Weitao Yang
Abstract: In the effort to develop novel functional materials and advanced devices based on them, first-principles or ab initio simulations are playing an increasingly important role by providing atomistic information that are not easily accessible in experiments. In this respect, a key ingredient that is still immature and should be further developed is the capability to treat non-equilibrium open junction systems under finite bias in a first-principles manner. For example, for graphene electrode-based van der Waals 2D tunneling transistors, ab initio simulations are currently not possible due to the inherent limitations of the standard approach combining density functional theory (DFT) and non-equilibrium Green's function (NEGF) formalisms [1-2]. In this talk, I will discuss the formulation and applications of the multi-space constrained-search DFT (MS-DFT) formalism we have been developing at KAIST for the past decade or so [1-4]. Seeking an alternative to the standard Landauer picture for quantum transport, we first propose a viewpoint that maps quantum transport processes to space-resolved (drain-to-source) optical excitation counterparts. The multi-space excitation picture for quantum transport then allows the formulation of microcanonical approaches for quantum transport, and the resulting MS-DFT provides unique opportunities in understanding and designing nanoscale devices in operando conditions. For example, unlike in the grand-canonical DFT-NEGF, the non-equilibrium total energy as well as quasi-Fermi level or voltage drop profile information can be obtained within the microcanonical MS-DFT [3,4]. As an appropriate thermodynamic potential for biased electrode/channel interfaces, I then establish the concept of electric enthalpy of formation. Key initial results obtained for electrified water/electrode interfaces will be outlined [5].