Theory for New Carbon-Based Materials

1992 ◽  
Vol 270 ◽  
Author(s):  
D.W. Brenner ◽  
R.C. Mowrey ◽  
J. W. Mintmire ◽  
J.A. Harrison ◽  
D.H. Robertson ◽  
...  

ABSTRACTWe review results of our local-density-functional-based cluster calculations and molecular dynamics simulations of fullerenes and related structures. These include predictions of cohesive energies, electronic structures, and photoelectron spectra for a number of pure and chemically substituted fullerenes, studies of the resilience of C60 under severe compression and during surface collisions, simulations of the trapping of Hein the interior of C60, predictions of the strain energy, electronic and elastic properties of graphitic tubules, and simulations of the folding and curling of graphitic ribbons.

1991 ◽  
Vol 43 (17) ◽  
pp. 14281-14284 ◽  
Author(s):  
J. W. Mintmire ◽  
B. I. Dunlap ◽  
D. W. Brenner ◽  
R. C. Mowrey ◽  
C. T. White

1992 ◽  
Vol 247 ◽  
Author(s):  
B. I. Dunlap ◽  
J. W. Mintmire ◽  
D. H. Robertson ◽  
D. W. Brenner ◽  
R. C. Mowrey ◽  
...  

ABSTRACTWe have calculated the electronic structure of icosahedrai C60H60 and tetrahedral C60H60 via an all-electron Gaussian-orbital based local-density functional approach. The one-electron wavefunctions and eigenvalues have been used in a first-order time-dependent perturbation theoretic calculation of the spherically averaged X-ray and ultraviolet pho-toemission cross-sections for these molecules.


1996 ◽  
Vol 449 ◽  
Author(s):  
Petra Stumm ◽  
D. A. Drabold

ABSTRACTMolecular dynamics simulations are employed to study defects in GaN. We use local basis density functional theory within the local density approximation where charge transfer between the ions is included in an approximate fashion. We find good agreement for the band structure of wurtzite and zincblende GaN compared to other recent calculations, suggesting the suitability of our method to describe GaN. A 96 atom GaN supercell is used to study the relaxations and electronic properties of common defects in the crystal structure, including Ga and N vacancies and antisites. We analyze the electronic signatures of these defects.


1993 ◽  
Vol 316 ◽  
Author(s):  
Bernard A. Pailthorpe

ABSTRACTThe synthesis of amorphous diamond thin films has been studied previously by classical molecular dynamics computer simulations utilising Stillinger Weber potentials, reparameterised to describe bonding in carbon. The simulations provided insight into the surface processes occuring during thin film growth and showed the role of stress and an energy window in promoting amorphous diamond formation from carbon ion beams. However, more realistic simulations require a full treatment of quantum effects to describe adequately chemical bonding and electronic properties. Local Density Functional theories and the Car-Parrinello molecular dynamics algorithm have proved to be successful and offer a route to first-principles materials design. We are using these techniques to investigate bonding and structure in small carbon clusters and to study doping of diamond required to fabricate electronic devices. Results are presented for a novel, three dimensional, neutral carbon-11 cluster which was studied by ab initio molecular dynamics simulations confirming that, while the 3D structure is stable, the ring is the lower energy structure. However, the 3D structure deforms rapidly to a more open structure of the same topology which is dynamically stable during simulated annealing up to 2000K. Higher quality calculations indicate that new, lower symmetry bonding arrangements form also. Attempts to enclose lithium or boron atoms within the Cl 1 cage caused heating and ultimate rupture into smaller fragments.


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