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Theoretical study of the nucleation/growth process of carbon clusters under pressure
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10.1063/1.2943679
/content/aip/journal/jcp/129/2/10.1063/1.2943679
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/2/10.1063/1.2943679

Figures

Image of FIG. 1.
FIG. 1.

Schematic carbon phase diagram proposed by Viecelli and Ree (Ref. 9). CJ conditions for the detonation products of some carbon-rich explosives are represented (blue triangle: nitromethane, red circle: TATB, orange square: TNT). The dashed lines are an approximation to the displacement of the coexistence lines for fixed size carbon clusters.

Image of FIG. 2.
FIG. 2.

Time evolution of the nucleation/growth mechanism for a 400 atom box at and .

Image of FIG. 3.
FIG. 3.

Same as Fig. 2 for a 10 800 atom box.

Image of FIG. 4.
FIG. 4.

Time evolution of the hybridization distribution of the and simulation (400 atoms). Blue crosses: isolated atoms. Green circles: dimers. Orange squares: chains and rings. Red diamonds: structures. Purple triangles: structures. Notice the hybridization jumps from to at and .

Image of FIG. 5.
FIG. 5.

Topology of the carbon clusters obtained at the end of the nucleation/growth simulations in vacuum. Left column: simulations at . Right column: simulations at . The total simulation time is for all cases.

Image of FIG. 6.
FIG. 6.

Time evolution of the average cluster size (logarithmic scale) for the simulated densities (black circles: , blue squares: , green diamonds: ) and temperatures (full symbols: , empty symbols: ). The single carbon atoms are not included in the average calculation. For each simulation, a succession of linear regimes can be observed indicating typical exponential growth laws . The evolution of the case is very fast and was not represented here for convenience.

Image of FIG. 7.
FIG. 7.

Time evolution of the nucleation/growth mechanism under pressure for , , and (case C of Fig. 9). The small black dots represent the rare gas atoms.

Image of FIG. 8.
FIG. 8.

Same as Fig. 4 for the and simulation with argon.

Image of FIG. 9.
FIG. 9.

Snapshots of the simulation box at the end of each trajectory. The small black dots represent the rare gas atoms. Left column: simulations at . Right column: simulations at . The pressure and the total integration time are specified in each case.

Image of FIG. 10.
FIG. 10.

plot of the data from Table III. Black dots: fullerene structures of Yoshida (Ref. 24), red cross: structure from our simulation at and . Note the increase in pressure when changing from the optimized fullerene structures to the nonideal structures grown in our simulations.

Image of FIG. 11.
FIG. 11.

Same as Fig. 6 for the simulated densities (green circles: , red squares: , blue diamonds: ) and temperatures (full symbols: , empty symbols: ). The growth velocity has been evaluated using linear regressions. The parameters are given in Table IV.

Tables

Generic image for table
Table I.

Simulation details for the nucleation/growth simulations in vacuum and under pressure, including the carbon density and the total density for the simulations under pressure. The hybridization distribution, the pressure, and the mean potential energy at the end of each simulation are presented. At , the reference energies per atom in graphite and diamond are , and , respectively.

Generic image for table
Table II.

Fitted parameters for the exponential growth laws plotted in Fig. 6. Only the slowest regime of each case is considered. Extrapolations to the time needed to grow detonationlike carbon clusters (, atoms) are given.

Generic image for table
Table III.

Estimation of the critical pressure required to activate a fullerene/diamond transition for different cluster sizes. is the differene in potential energy between diamond and fullerene, and are the volumes of the fullerene and the diamond clusters, respectively, and is the critical pressure, as defined in Eq. (3). Units: in eV, and in , and in GPa. The reference structures for fullerenes up to 100 atoms are taken from Yoshida’s fullerene library (Ref. 24). For , the reference is the cluster obtained at the end of our simulation at and .

Generic image for table
Table IV.

Calculated growth rates and extrapolated times needed to form a 50.000 atom detonation carbon cluster.

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/content/aip/journal/jcp/129/2/10.1063/1.2943679
2008-07-09
2014-04-25
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Theoretical study of the nucleation/growth process of carbon clusters under pressure
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/2/10.1063/1.2943679
10.1063/1.2943679
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