Stability of charged Si-doped heterofullerenes: A first-principles molecular dynamics study

Abstract

We study the structural stability of the singly and doubly charged ͑positively and negatively͒ Si-doped heterofullerene C 30 Si 30 via density-functional theory calculations combined with first-principles molecular dynamics. Geometry optimization aimed at establishing the most stable configurations at T = 0 K shows that C 30 Si 30 undergoes very limited changes in the bond lengths after addition or extraction of one or two electrons. Consideration of thermal motion reveals that the dynamical stability is not significantly altered in C 30 Si 30 − with respect to the neutral case. On the contrary, Si-Si and C-C bond stretching followed by rapid fragmentation, occurring in less than 1 ps, are observed for C 30 Si 30 −− . This effect is encountered in two sets of calculations performed with the periodic cell and the isolated cell boundary conditions for the heterofullerene. In the periodic case, fragmentation is due to the predominance of Si atoms carrying charges of equal sign in the Si-rich portion of the cage. In the isolated case, the number of neighboring charges of equal sign is reduced but the strength of the residual repulsive interaction is sufficient to destabilize the network at finite temperature. The lack of stability of doubly charged Si-doped heterofullerenes confirms that the observed charged species are the singly charged ones.

Ground States of Silicon-Multisubstituted Fullerene: First-Principles Calculations and Monte Carlo Simulations

“…It appears that increased doping does not stretch the Si-Si bonds significantly, confirming the trend observed in Ref. [15].…”

Scientific Surgery

“…In theory, a number of heterofullerenes containing one or more heteroatoms have been investigated, such as B,14 Si,15 Ti,16 N,17 O,18 S,19 and Xe,20 among which oxygen‐doped fullerenes have been relatively more intensively studied. The neutral C 59 O and positive species C 59 O 2+ were predicted to have cage‐opened and cage‐closed structures, respectively 19.…”

Structural and electronic properties of boron- and nitrogen-doped SinCn(n= 7–15) clusters: a theoretical investigation

“…Over the past few years, the study of the structural and electronic properties of semiconductor nanoclusters has been an extremely active area of research due to their importance in nanoscience and nanotechnology [1][2][3][4]. Silicon carbide clusters are the subjects of intensive studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Recent theoretical investigations (for example, [14][15][16][17][18][19][20]) indicated that small SiC clusters prefer three-dimensional cage-like structures, and the distinct separation between the two parts of Si atoms and C atoms is energetically favourable.…”

“…Silicon carbide clusters are the subjects of intensive studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Recent theoretical investigations (for example, [14][15][16][17][18][19][20]) indicated that small SiC clusters prefer three-dimensional cage-like structures, and the distinct separation between the two parts of Si atoms and C atoms is energetically favourable. However, because of the lack of sp 2 hybridization of the valence orbitals of silicon atoms in SiC clusters, the empty SiC cage-like structures are likely unstable.…”