Shobhna Dhiman

DFT study of Al doped armchair SWCNTs

Electronic properties of endohedrally doped armchair single-walled carbon nanotubes (SWCNTs) with a chain of six Al atoms have been studied using ab-initio density functional theory. We investigate the binding energy/atom, ionization potential, electron Affinity and Homo-Lumo gap of doped armchair SWNTs from (4,4) to (6,6) with two ends open. BE/dopant atom and ionization potential is maximum for (6, 6) doped armchair carbon nanotube; suggest that it is more stable than (4, 4) and (5, 5) doped tubes. HOMO - LUMO gap of Al doped arm chair carbon nanotubes decreases linearly with the increase in diameter of the tube. This shows that confinement induce a strong effect on electronic properties of doped tubes. These combined systems can be used for future nano electronics. The ab–initio calculations were performed with SIESTA code using generalized gradient approximation (GGA).

Silver clusters encapsulated in C60: A density functional study

We explore the possibility of formation of endohedral complexes of Agn atoms (n=1-9) inside C60 molecule using density functional theory and molecular dynamics. The obtained results reveal that Agn (n=8) atoms can form stable complexes with the C60 molecule. Encapsulation of large number of Agn atoms (n>8) make C60 cage instable, showing distortion of cage. Binding energy/atom increases with the number of Ag atoms up to n=4, after that it increases. Ionization potential decreases till n=4 and then increases, electron affinity increases till n=4 and then shows oscillatory nature as a function of Ag atoms inside the cage. Homo –Lumo gap shows no systematic pattern. Our results agreed well with the data available.

Density functional study of structural and electronic properties of Aln@C60

Fullerene derivatives have been shown to make contributions in many types of applications. Ab initio investigation of structural and electronic properties of aluminum doped endohedral fullerene has been performed using numerical atomic orbital density functional theory. We have obtained ground state structures for Aln@C60 (n=1–10). Which shows that C60 molecule can accommodate maximum of nine aluminum atoms, for n > 9 the cage eventually break. Encapsulated large number of aluminum atoms leads to deformation of cage with diameter varies from 7.16A to 7.95A. Binding energy/Al atom is found to increase till n = 4 and after that it decreases with the number of Al atoms with a sudden increase for n=10 due to breakage of C60 cage and electronic affinity first increases till n=4 then it decreases up to n=9 with a sharp increase for n=10. Ionization potential also first increases and then decreases. Homo-Lumo gap decreases till n=3 with a sharp increase for n=4, after that it shows an oscillatory nature. The res...

Ab initio study of structural and electronic properties of Cun@C60

Ab initio investigation of structural and electronic properties of copper doped endohedral fullerene has been performed using numerical atomic orbital density functional theory. We have obtained the ground state structures for Cun@C60 (n=1-10). Which shows that C60 molecule can accommodate maximum of nine copper atoms, for n > 9 the cage eventually break. Encapsulated large number of copper atoms leads to deformation of cage with diameter varies from 7.00A to 8.38A. Binding energy/Cu atom is found to increase till n = 4 and after that it decreases with the number of Cu atoms with a sudden increase for n=10 and electronic affinity increases till n=2 then decreases uniformly till up to n=7 with a further sharp decrease for n=10. Ionization potential and Homo-Lumo gap shows a oscillatory nature. The results obtained are consistent with available theoretical and experimental results. The ab-initio calculations were performed using SIESTA code with generalized gradient approximation (GGA).

Electronic Properties of Carbon Nanotubes Using Density Functional Theory

The electronic properties of zigzag (n,0) and armchair (n,n) single wall carbon nanotubes (SWCNTs) have been studied using ab‐initio density functional theory. We investigate the effect of diameter/length on binding energy/atom and Homo‐Lumo gap of zigzag SWNTs from (3,0) to (7,0) and armchair SWNTs from (3,3) to (7,7) with two ends open. B.E/atom decreases with increase in length of all the tubes leading to the stability of long tubes. Band gap decreases with increasing length of zigzag and armchair CNTs, but decrease is not monotonic. The ab–initio calculations were performed using SIESTA code using generalized gradient approximation (GGA).