Interaction sites of a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Na</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>ion and a Na atom with a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>60</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>molecule

Hira, Ajit; Ray, Asok

doi:10.1103/physreva.52.141

Cited by 24 publications

(18 citation statements)

References 52 publications

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“…Our results are consistent with experimental 18,28,40 and other theoretical 8,16 studies, which predicted an electronic transfer of about one electron from the singly occupied atomic orbital of the alkali atom to the lowest-unoccupied molecular orbital (LUMO) of C 60 . This behavior indicates a significant ionic bonding of the alkali atom with the fullerene.…”

supporting

confidence: 92%

“…As can be seen, H and P are the most stable configurations with a small preference of only 0.03 eV for the hexagon. [8] b DFT-LDA calculations [16] c Experimental data [29,40] These results are in agreement with the calculations performed by Hamamoto et al 16 who found H as the most stable configuration with a weak difference between H and P of about 0.05 eV. However, the adsorption energies reported in Ref.…”

supporting

confidence: 83%

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Nucleation of a sodium droplet onC60

et al. 2003

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We investigate theoretically the progressive coating of C60 by several sodium atoms. Density functional calculations using a nonlocal functional are performed for NaC60 and Na2C60 in various configurations. These data are used to construct an empirical atomistic model in order to treat larger sizes in a statistical and dynamical context. Fluctuating charges are incorporated to account for charge transfer between sodium and carbon atoms. By performing systematic global optimization in the size range 1 ≤ n ≤ 30, we find that NanC60 is homogeneously coated at small sizes, and that a growing droplet is formed above n ≥ 8. The separate effects of single ionization and thermalization are also considered, as well as the changes due to a strong external electric field. The present results are discussed in the light of various experimental data.

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supporting

confidence: 92%

supporting

confidence: 83%

Nucleation of a sodium droplet onC60

et al. 2003

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“…They concluded that a sodium droplet is formed on the surface of the fullerene. These apparent contradictory results are surprising, as far as they rely on similar experimental conditions but different interpretations.The situation is in fact even more intricate due to the variety of theoretical conclusions on the very same systems [9,10,11,12]. With the exception of the study by Rubio and coworkers [9], which assumes complete wetting of C 60 by sodium in a continuous two-shell jellium description, the electronic structure calculations by Hira and Ray [10,11], and by Hamamoto et al…”

mentioning

confidence: 99%

“…With the exception of the study by Rubio and coworkers [9], which assumes complete wetting of C 60 by sodium in a continuous two-shell jellium description, the electronic structure calculations by Hira and Ray [10,11], and by Hamamoto et al…”

mentioning

confidence: 99%

Wetting-to-Nonwetting Transition in Metal-CoatedC60

et al. 2003

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Based on ab initio and density-functional theory calculations, an empirical potential is proposed to model the interaction between a fullerene molecule and many sodium atoms. This model predicts homogeneous coverage of C60 below 8 Na atoms, and a progressive droplet formation above this size. The effects of ionization, temperature, and external electric field indicate that the various, and apparently contradictory, experimental results can indeed be put into agreement. PACS numbers: 61.48.+c,36.40.Qv,34.70.+e Fullerene molecules are now commonly used as building blocks of complex materials having unusual physical and chemical properties [1]. The possibilities offered by molecules such as C 60 or C 70 in terms of electric or optical devices have laid ground for the rapidly expanding nanotechnology area. The interaction between fullerenes and alkali atoms has attracted a lot of attention after the discovery of superconductivity in the K 3 C 60 solid [2]. Sodium-C 60 compounds have also received much attention [3,4]. More recently, several groups investigated experimentally the gas phase properties of exohedral alkali-C 60 compounds [5,6,7], to further predict the solid state of alkali-doped fullerite.Using mass spectrometry, Martin and coworkers [6] inferred from the most stable "magic numbers" that sodium covers the C 60 molecule in a continuous and homogeneous fashion, and that metallic bonding starts above 6 metal atoms. Palpant and coworkers [7] deduced from photoelectron spectroscopy measurements that coating proceeds by trimers units rather than single atoms. They also estimated that metallic bonding only appears at n = 13 sodium atoms. Very recently, Dugourd and coworkers [8] measured the electric polarizability of Na n C 60 clusters in the range 1 ≤ n ≤ 34. They concluded that a sodium droplet is formed on the surface of the fullerene. These apparent contradictory results are surprising, as far as they rely on similar experimental conditions but different interpretations.The situation is in fact even more intricate due to the variety of theoretical conclusions on the very same systems [9,10,11,12]. With the exception of the study by Rubio and coworkers [9], which assumes complete wetting of C 60 by sodium in a continuous two-shell jellium description, the electronic structure calculations by Hira and Ray [10,11], and by Hamamoto et al.[12] reach different conclusions as to whether the Na 2 molecule remains as a dimer or dissociates into atoms, which locate on opposite sides of C 60 . At the unrestricted HartreeFock level, Hira and Ray find that charge transfer is negligible in NaC 60 , in apparent contradiction with experiments [7,8], and also that Na 2 remains as a dimer loosely bound to C 60 . On the other hand, the more realistic density-functional theory (DFT) calculations performed by Hamamoto and coworkers [12] at the local density approximation level tend to favor regular coating, preferentially by trimers, in agreement with the picture of Palpant et al. [7]. However, all these ab initio investig...

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“…[1][2][3][4] Detailed investigations on doped fullerene molecules with dopant atoms in substitutional (where the dopant substitutes one carbon atom from the cage), endohedral (where the dopant is inside the fullerene shell), and exohedral (where the dopant is outside fullerene shells) sites of the fullerene cage have been carried out experimentally as well as theoretically. [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] A large number of impurity atoms including the rare gas atoms, 5-9 lanthanides 10-12 alkali metals, 10 13-19 alkali earth metal, 20-21 transition metals, [21][22][23][24][25][26][27][28] main group elements [29][30] etc., have been successfully used in the doping of fullerenes. The direct production of fullerenes in the presence of foreign species may lead to endohedral [8][9][10] or substitutional fullerenes.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Impurity Atom with C<SUB>60</SUB> Fullerene Cage: A Density Functional Theory (DFT) Analysis

Nigam¹,

Majumder²

2009

Jnl of Comp & Theo Nano

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We report the ground state geometry and electronic structure of MC 60 clusters (M = Rb, Sr, Hf, Ga, Ge, Zn, As, Br). The calculations are performed using the density functional theory formalism under the Perdew-Burke-Erzerhof (PBE) exchange correlation energy functional. It is found that the preferred location of the M atom depends on their atomic size and nature of interaction with C 60 cage. While metal atoms like Sr, and Hf prefer encapsulation inside the cage by coordinating the hexagonal face, Ga caps the pentagon from outside. Among other atoms, Ge and As adsorb on the bridge site of the cage and Br sits on the top site. The stability analysis based on total energy considerations suggest that while Hf doping enhances the stability most, Zn with C 60 shows weakest interaction. In order to understand the energy barrier to insert impurity atom inside the cage wall, detailed calculations have been carried out to draw the energy landscape along the target path of 8.3 Å distance as the impurity atoms travel from outside (5 Å) to the center of the cage.

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Interaction sites of aNa+ion and a Na atom with aC60molecule

Cited by 24 publications

References 52 publications

Nucleation of a sodium droplet onC60

Nucleation of a sodium droplet onC60

Wetting-to-Nonwetting Transition in Metal-CoatedC60

Interaction of Impurity Atom with C<SUB>60</SUB> Fullerene Cage: A Density Functional Theory (DFT) Analysis

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