Kwang S. Kim

Bio: Kwang S. Kim is an academic researcher from Ulsan National Institute of Science and Technology. The author has contributed to research in topics: Ab initio & Graphene. The author has an hindex of 97, co-authored 642 publications receiving 62053 citations. Previous affiliations of Kwang S. Kim include Asia Pacific Center for Theoretical Physics & IBM.

The Luttinger–Ward functional approach in the Eliashberg framework: a systematic derivation of scaling for thermodynamics near the quantum critical point

Abstract: Scaling expressions for the free energy are derived, using the Luttinger–Ward (LW) functional approach in the Eliashberg framework, for two different models of the quantum critical point (QCP). First, we consider the spin-density-wave model for which the effective theory is the Hertz–Moriya–Millis theory, describing the interaction between itinerant electrons and collective spin fluctuations. The dynamics of the latter are described using a dynamical exponent z depending on the nature of the transition. Second, we consider the Kondo breakdown model for QCPs, one possible scenario for heavy-fermion quantum transitions, for which the effective theory is given by a gauge theory in terms of conduction electrons, spinons for localized spins, holons for hybridization fluctuations, and gauge bosons for collective spin excitations. For both models, we construct the thermodynamic potential, in the whole phase diagram, including all kinds of self-energy corrections in a self-consistent way, at the one-loop level. We show how the Eliashberg framework emerges at this level and use the resulting Eliashberg equations to simplify the LW expression for the free energy. It is found that collective boson excitations play a central role. The scaling expression for the singular part of the free energy near the Kondo breakdown QCP is characterized by two length scales: one is the correlation length for hybridization fluctuations, and the other is that for gauge fluctuations, analogous to the penetration depth for superconductors.

A universal screening strategy for the accelerated design of superior oxygen evolution/reduction electrocatalysts

Abstract: Despite advanced computational methods, it is not practical to utilize high-throughput computational screening for a large number of candidates for multi-step reactions due to intercorrelation between reaction intermediates. However, we have devised a universal computational screening strategy that can accelerate the prediction of the theoretical overpotential (ηDFT) for the Oxygen Evolution/Reduction Reaction (OER/ORR) by using only the adsorption free energy of O*. Our accelerated screening strategy can effectively reduce the computing time by skipping the costly calculations of adsorption free energies of OH* and OOH*. Besides, the efficiency of the accelerated screening strategy was verified using 1008 combinations of single-atom-anchored transition metal dichalcogenides. The given candidate materials are rapidly screened using our strategy and finally 32 promising catalysts are found which have a lower ηDFT than state-of-the-art commercial IrO2 for the OER and Pt for the ORR. Our screening strategy that uses a sequential process can narrow down the candidate space, and enables practical high-throughput computational screening of oxygen-involved reactions even for a large number of candidates.

pH-Responsive self-duplex of PyA-substituted oligodeoxyadenylate in graphene oxide solution as a molecular switch

Abstract: In this paper, we demonstrated a highly discriminated and reliable molecular switch based on the interaction between the self-duplex of PyA-substituted oligodeoxyadenylate and graphene oxide in aqueous solution. This system showed a clear on/off state through the association and dissociation of PyA-modified oligodeoxynucleotide with graphene oxide in manipulated pH conditions, high amplitude efficiency for at least 50 cycles, and rapid response within seconds. Our molecular switch system has high reproducibility and simple operation by using pH stimulus.

Insights into the Nature of SiH4−BH3 Complex: Theoretical Investigation of New Mechanistic Pathways Involving SiH3• and BH4• Radicals

Abstract: We have investigated a new type of interaction between silane (SiH4) and borane (BH3) using high level ab initio calculations. The SiH4−BH3 complex is found to be extremely stable with the formation of a bridged hydrogen bond between SiH4 and BH3. Hence, it might have a hitherto unknown role in the mechanism of chemical vapor deposition (CVD), which is employed in the fabrication of boron doped silicon semiconductor materials. In an attempt to unravel this role and the underlying reasons responsible for the stability of this complex, we have carried out a detailed analysis based on the structure and molecular orbitals. The results indicate that the binding strength and electronic character of the bridged hydrogen bond in the SiH4−BH3 complex is between those observed in double hydrogen bridged B2H6 and mono-hydrogen bridged anion B2H7-. In contrast to B2H6 and B2H7-, it should be noted that the complex is stabilized by direct strong electrostatic interaction between the positively charged Si atom and the ...

Dissolution of a base (RbOH) by water clusters.

Abstract: Density functional and ab intio calculations are employed in order to understand the base dissociation of rubidium hydroxide by water molecules. The hydrated structures, stabilities, thermodynamic quantities, dissociation energies, infrared spectra, and electronic properties of RbOH(H2O)(n = 0-5) are investigated. With the successive addition of water molecules to RbOH, the Rb-OH bond lengthens significantly from 2.45 angstroms for n = 0 to 3.06 angstroms for n = 5. It is interesting to note that four water molecules are needed for the stable dissociation of RbOH (as an almost dissociate conformation) and five water molecules are needed for the complete dissociation without any Rb-OH stretch mode, in contrast to the same group base of CsOH which requires only three water molecules for an almost dissociate conformation and four water molecules for the complete dissociation.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials

Abstract: QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). The acronym ESPRESSO stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization. It is freely available to researchers around the world under the terms of the GNU General Public License. QUANTUM ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively parallel architectures, and a great effort being devoted to user friendliness. QUANTUM ESPRESSO is evolving towards a distribution of independent and interoperable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。