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.

Fulgides as Light-Driven Molecular Rotary Motors: Computational Design of a Prototype Compound.

Abstract: A new family of light-driven molecular rotary motors utilizing the fulgide motif is proposed and its prototype molecule is studied by quantum chemical calculations and nonadiabatic molecular dynamics simulations. The new motor performs pure unidirectional axial rotation of the rotor blade with high quantum efficiency (ϕ ∼ 0.55–0.68) and ultrafast dynamics (⟨t⟩S1 ∼ 200–300 fs) of its successive photoisomerization steps. The photocyclization reaction typical of fulgide compounds is blocked by the design of the new motor and never occurred in the molecular dynamics simulations. The new motors can be synthesized from easily available precursors. In view of its remarkable photoisomerization ability, the new motor represents a prospective class of compounds for the use in nanosized molecular devices.

Antimony nanowires self-assembled from Sb nanoparticles

Abstract: For the first time, we introduced a simple method of synthesizing segregated thin antimony nanowires based on the principle that nanoparticles can spontaneously self-assemble into crystalline nanowires (∼20 nm) in the absence of any rigid templates at room temperature. By collecting electron energy loss spectra from individual Sb nanowires with different diameters, we investigated the effect of nanowire diameter on plasmon excitations in Sb nanowires. As the diameter of Sb nanowire decreases, we find that the peak energy of surface plasmon shifts toward the lower energy.

Water heptamer with an excess electron: Ab initio study

Abstract: The electron–water heptamer is one of the “magic” numbers in the mass spectra of electron–water clusters, but up to now the structure of the electron–water heptamer is not known. Thus we have investigated a number of low-energy structures, and report the lowest-energy structure using ab initio calculations. The relative energies, vertical electron-detachment energies, and OH vibrational frequencies of several lowest energy conformers are discussed. As in the case of e−(H2O)6, the electron affinity for e−(H2O)7 is predicted to be positive, which would explain the intense peak observed in the time-of-flight mass spectra.

The origin of dips for the graphene-based DNA sequencing device

Abstract: We recently proposed an ultrafast DNA sequencing method that electrically distinguishes different nucleobases on a graphene nanoribbon (GNR), utilizing π–π interaction. Analyzing the molecular orbitals (MOs) and the features of dips in conductance for our GNR-based sequencing device, we prove that the Fano resonance is responsible for the characteristic dips of each nucleobase.

In Search of a Two-Dimensional Material for DNA Sequencing

Abstract: We analyze the transmission of narrow semiconducting nanoribbons designed from two-dimensional (2D) layered materials such as graphene, silicene, hexagonal boron nitride (hBN), and molybdenum disulfide (MoS2). The Fano resonance driven dips in the transmission, when nucleobases stack with graphene nanoribbon, are known to be useful for DNA sequencing. For graphene and hBN nanoribbons the transmission dips are distinct for each nucleobase, but with a larger band gap for the latter case. For silicene nanoribbon the dips due to different nucleobases are somehow less clear. The transmission of the MoS2 nanoribbon is unpromising for DNA sequencing as the dip in the transmission is not useful to identify any of the nucleobase. The dip positions in the transmission shift linearly with bias voltage. This shift depends on the nanoribbon used and the orientation of the DNA base. Hence, edge-modified hBN nanoribbons with a reduced band gap could be an alternative to graphene nanoribbon (GNR) for DNA sequencing and r...

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。