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Author |
Fukuhara, S.; Bal, K.M.; Neyts, E.C.; Shibuta, Y. |
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Title |
Entropic and enthalpic factors determining the thermodynamics and kinetics of carbon segregation from transition metal nanoparticles |
Type |
A1 Journal article |
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Year  |
2021 |
Publication |
Carbon |
Abbreviated Journal |
Carbon |
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Volume |
171 |
Issue |
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Pages |
806-813 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The free energy surface (FES) for carbon segregation from nickel nanoparticles is obtained from advanced molecular dynamics simulations. A suitable reaction coordinate is developed that can distinguish dissolved carbon atoms from segregated dimers, chains and junctions on the nanoparticle surface. Because of the typically long segregation time scale (up to ms), metadynamics simulations along the developed reaction coordinate are used to construct FES over a wide range of temperatures and carbon concentrations. The FES revealed the relative stability of different stages in the segregation process, and free energy barriers and rates of the individual steps could then be calculated and decomposed into enthalpic and entropic contributions. As the carbon concentration in the nickel nanoparticle increases, segregated carbon becomes more stable in terms of both enthalpy and entropy. The activation free energy of the reaction also decreases with the increase of carbon concentration, which can be mainly attributed to entropic effects. These insights and the methodology developed to obtain them improve our understanding of carbon segregation process across materials science in general, and the nucleation and growth of carbon nanotube in particular. |
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Wos |
000598371500084 |
Publication Date |
2020-09-25 |
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ISSN |
0008-6223 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.337 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
Scientific Research, 19H02415 ; JSPS, 18J22727 ; Japan Society for the Promotion of Science; JSPS; JSPS; FWO; Research Foundation; Flanders, 12ZI420N ; This work was supported by Grant-in-Aid for Scientific Research (B) (No.19H02415) and Grant-in-Aid for JSPS Research Fellow (No.18J22727) from Japan Society for the Promotion of Science (JSPS), Japan. S.F. was supported by JSPS through the Program for 812 |
Approved |
Most recent IF: 6.337 |
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Call Number |
PLASMANT @ plasmant @c:irua:172452 |
Serial |
6421 |
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Author |
Bal, K.M.; Fukuhara, S.; Shibuta, Y.; Neyts, E.C. |
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Title |
Free energy barriers from biased molecular dynamics simulations |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Journal Of Chemical Physics |
Abbreviated Journal |
J Chem Phys |
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Volume |
153 |
Issue |
11 |
Pages |
114118 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Atomistic simulation methods for the quantification of free energies are in wide use. These methods operate by sampling the probability density of a system along a small set of suitable collective variables (CVs), which is, in turn, expressed in the form of a free energy surface (FES). This definition of the FES can capture the relative stability of metastable states but not that of the transition state because the barrier height is not invariant to the choice of CVs. Free energy barriers therefore cannot be consistently computed from the FES. Here, we present a simple approach to calculate the gauge correction necessary to eliminate this inconsistency. Using our procedure, the standard FES as well as its gauge-corrected counterpart can be obtained by reweighing the same simulated trajectory at little additional cost. We apply the method to a number of systems—a particle solvated in a Lennard-Jones fluid, a Diels–Alder reaction, and crystallization of liquid sodium—to demonstrate its ability to produce consistent free energy barriers that correctly capture the kinetics of chemical or physical transformations, and discuss the additional demands it puts on the chosen CVs. Because the FES can be converged at relatively short (sub-ns) time scales, a free energy-based description of reaction kinetics is a particularly attractive option to study chemical processes at more expensive quantum mechanical levels of theory. |
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Wos |
000574665600004 |
Publication Date |
2020-09-21 |
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Series Issue |
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Edition |
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ISSN |
0021-9606 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.4 |
Times cited |
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Open Access |
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Notes |
Japan Society for the Promotion of Science, 19H02415 18J22727 ; Fonds Wetenschappelijk Onderzoek, 12ZI420N ; This work was supported, in part, by a Grant-in-Aid for Scientific Research (B) (Grant No. 19H02415) and Grant-in-Aid for a JSPS Research Fellow (Grant No. 18J22727) from the Japan Society for the Promotion of Science (JSPS), Japan. K.M.B. was funded as a junior postdoctoral fellow of the FWO (Research Foundation – Flanders), Grant No. 12ZI420N. S.F. was supported by JSPS through the Program for Leading Graduate Schools (MERIT). The computational resources and services used in this work were provided by the HPC core facility CalcUA of the Universiteit Antwerpen, and VSC (Flemish Supercomputer Center), funded by the FWO and the Flemish Government. The authors are grateful to Pablo Piaggi for making the pair entropy CV code publicly available. |
Approved |
Most recent IF: 4.4; 2020 IF: 2.965 |
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Call Number |
PLASMANT @ plasmant @c:irua:172456 |
Serial |
6420 |
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Author |
Fukuhara, S.; Bal, K.M.; Neyts, E.C.; Shibuta, Y. |
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Title |
Accelerated molecular dynamics simulation of large systems with parallel collective variable-driven hyperdynamics |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Computational Materials Science |
Abbreviated Journal |
Comp Mater Sci |
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Volume |
177 |
Issue |
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Pages |
109581 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The limitation in time and length scale is a major issue of molecular dynamics (MD) simulation. Although several methods have been developed to extend the MD time scale, their performance usually deteriorates with increasing system size. Therefore, an acceleration method which is applicable to large systems is required to bridge the gap between the MD simulations and target phenomena. In this study, an accelerated MD method for large system is developed based on the collective variable-driven hyperdynamics (CVHD) method [K.M. Bal and E.C. Neyts, 2015]. The key idea is to run CVHD in parallel with rate control and accelerate multiple possible events simultaneously. Using this novel method, carbon diffusion in bcc-iron bicrystal with grain boundary is examined as an application for practical materials. Carbon atoms reaching at the grain boundary are trapped whereas carbon atoms in the bulk region diffuse randomly, and both dynamic regimes can be simultaneously accelerated with the parallel CVHD technique. |
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Wos |
000519576300001 |
Publication Date |
2020-02-08 |
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ISSN |
0927-0256 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.3 |
Times cited |
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Open Access |
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Notes |
JSPS, J22727 ; Japan Society for the Promotion of Science; This work was supported by Grant-in-Aid for Scientific Research (B) (No.19H02415) and Grant-in-Aid for JSPS Research Fellow (No.18J22727) from Japan Society for the Promotion of Science (JSPS), Japan. S.F. was supported by JSPS through the Program for Leading Graduate Schools (MERIT). Data availability The data required to reproduce these findings are available from the corresponding authors upon reasonable request. |
Approved |
Most recent IF: 3.3; 2020 IF: 2.292 |
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Call Number |
PLASMANT @ plasmant @c:irua:166773 |
Serial |
6333 |
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