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.

Molecular architecture using novel types of non-covalent π-interactions involving aromatic neutrals, aromatic cations and π-anions

Abstract: A solid-state complex utilizing non-covalent interactions between two aromatic cations is synthesized and characterized. The X-ray study of the structure shows that the anion templated π+–π+ interactions are the major driving force in the crystal packing, while π+–π, π–π, π–anion and π+–anion interactions assist the overall stabilization of self-assembly. In addition, we also identify the cation-mediated non-covalent interaction between two π anions (π−–π− interaction). The interaction energies of the important driving forces (π+–π+, π+–π, π–anion, π+–anion, and π−–π− interactions) observed in the crystal structure are calculated using dispersion-corrected density functional theory (DFT-D).

Charge transfer to solvent (CTTS) energies of small X−(H2O)n=1–4 (X=F, Cl, Br, I) clusters: Ab initio study

Abstract: Charge transfer to solvent (CTTS) energies of small halide–water clusters, X−(H2O)n=1–4 (X=F, Cl, Br, I) have been studied using first-order configuration interaction as well as time dependent discrete Fourier transform density functional methods The only available experimental data are the recently reported CTTS energies for I−(H2O)n=1–4 clusters by Johnson and co-workers [D Serxner, C E H Dessent, and M A Johnson, J Chem Phys 105, 7231 (1996)] These results are in good agreement with our predicted values The calculated CTTS energies indicate that there is regularity in the change of CTTS energies with respect to the change of halide anion as well as the cluster size Our investigations have shown that this observed trend of CTTS energies of X−(H2O)n clusters could be quantitatively explained by the ionization potential of the halide anions and the binding energies of the respective clusters

Structures, energetics, and spectra of fluoride–water clusters F−(H2O)n, n=1–6: Ab initio study

Abstract: F−(H2O)n (n=1–6) clusters have been studied using ab initio calculations. This is an extensive work to search for various low-lying energy conformers, for example, including 13 conformers for n=6. Our predicted enthalpies and free energies are in good agreement with experimental values. For n=4 and 6, both internal and surface structures are almost isoenergetic at 0 K, while internal structures are favored with increasing temperature due to the entropic effect. For n=5, the internal structure is favored at both 0 and 298 K under 1 atm. These are contrasted to the favored surface structures in other small aqua–halide complexes. The ionization potential, charge-transferto-solvent (CTTS) energy, and O–H stretching vibrational spectra are reported to facilitate future experimental work. Many-body interaction potential analyses are presented to help improve the potential functions used in molecular simulations. The higher order many-body interaction energies are found to be important to compare the energetics ...

Machine learning-based high throughput screening for nitrogen fixation on boron-doped single atom catalysts

Abstract: Production of ammonia via electrochemical nitrogen reduction reaction (NRR) has recently attracted much attention due to its potential to play a vital role in producing fertilizers and other chemicals. High throughput screening of electrocatalysts for the NRR requires numerous calculations in the search space, making the computational cost a bottleneck for predicting eligible electrocatalysts. Here we used a deep neural network (DNN) to predict efficient electrocatalysts for the NRR among boron(B)-doped graphene single atom catalysts (SACs). This model can noticeably reduce the time of computation by removing non-efficient catalysts from screening. Also, the adsorption energy and free energy can be predicted by the feature-based light gradient boosting machine (LGBM) model. These features represent the geometrical structure as well as bonding characteristics. Among the catalysts evaluated, three candidates were identified as very promising catalysts, offering excellent selectivity over the hydrogen evolution reaction (HER). CrB3C1 exhibited a minimal overpotential of 0.13 V for the NRR. This study provides a new pathway for the rational design of catalysts for nitrogen fixation by employing the most important features involved in the NRR by using machine learning methods.

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。