Barnali Bhattacharya

A first principle study of pristine and BN-doped graphyne family

Based on first principle calculation using generalized gradient approximation, we report electronic properties of graphyne and its related structures (graphdiyne, graphyne-3, graphyne-4). Boron and nitrogen atoms are systematically substituted into the position of carbon atom and the corresponding changes of the properties are reported. All the structures are found to be direct band gap semiconductors with band gap depending on the concentration and position of the doping material. Our band structure calculation clearly shows that the band gap can be tuned by B–N doping and the spin-polarized calculation depicts the nonmagnetic nature of these structures. The possibility of modulating the band gap provides flexibility for its use in nanoelectronic devices. Projected density of state (PDOS) analysis shed insights on the bonding nature of these novel materials, whereas from the view point of Crystal Orbital Hamilton Population (–COHP) analysis, the nature of chemical bonding between neighbouring atoms and the orbital participating in bonding and antibonding have been explored in details.

First principle study of adsorption of boron-halogenated system on pristine graphyne

To ensure the possibility of using graphyne as a gas sensor, we have studied the adsorption of boron-halogenated system on pristine graphyne with the help of density functional theory using generalized gradient approximation. Depending on binding energy the most stable orientation, adsorption strength and optimal distance between the above mention molecules and graphyne surface have been determined. The band gap of graphyne slightly increases with the adsorption of the boron-halogenated system. The graphyne system behaves as n-type semiconductor when it interacts with BI3 and BCl3 molecules, and it behaves as p-type semiconductor when interaction with BF3 molecule takes place. Our result reveals that the electronic properties of pristine graphyne are highly influenced by the adsorption of boron-halogenated molecule. We have observed that pristine graphyne has zero electric dipole moment, but with the interaction of boron-halogenated molecule, a significant change in the electric dipole moment takes place. Hence, by measuring the electric dipole moment change, graphyne-based gas sensor can be design for the detection of above-mentioned molecules.

Nickel cluster functionalised carbon nanotube for CO molecule detection: a theoretical study

ABSTRACT Using spin-polarised density functional theory calculation single-walled carbon nanotube (SWCNT) whose sidewall is functionalised with nickel cluster is studied for its possible application in CO molecule sensing. We have chosen (6,0) SWCNT functionalised with Ni13 cluster as the model for nanotube-cluster system. Changes in the properties of nanotube-cluster system brought by the CO molecule are reported. The CO molecule binding is energetically more favourable to the nanotube-cluster system than the pristine nanotube. The electronic properties are investigated in terms of density of states and bandstructure calculations. Pristine carbon nanotubes are intrinsically non-magnetic but nanotubes functionalised with nickel cluster are observed to have a huge magnetic moment which reduced on adsorbing CO molecule. The change in magnetisation upon CO adsorption may be detected using a suitable magnetometer. This result suggests the possibility of using carbon nanotube-cluster system to detect CO molecules. Bader charge analysis shows that CO molecule withdraws electronic charge from the cluster atoms. Nature of chemical bonding is studied with crystal orbital Hamilton population (–COHP) analysis.

Density functional theory study of pristine and transition metal doped fullerene

Density functional theory (DFT) methodology have been used to investigate the global reactivity parameters and non-linear optical properties of pristine C20 and C19X (X = Fe, Co) fullerenes. We find that noticeable structural change takes place in C20 when one of its carbon atoms is substituted with Fe or Co. The energy gap of the doped fullerenes also decreases significantly making these more reactive as compared to C20. The negligible static first hyperpolarizability and zero dipole moment of C20 climb to a considerably higher value even for the presence of single dopant atom. Considering all the studied properties, it may be inferred that the applicability of C20 fullerene as a nanoelectronic and non-linear optical (NLO) material would increase on doping with Fe and Co atom. Specifically, C19Fe would be better among them.

The Influence of the Substitution of Transition Metals on Pristine C20: A DFT Study

The stabilities and reactivities of two transition metal (X=Cu, Zn)-doped structures of C20 fullerene have been investigated by density functional theory approach. We have observed a noticeable str...

Confinement of water molecule inside (2, 2) graphyne nanotube

Using density functional theory (DFT) calculations with generalized gradient approximation, the interaction between H2O molecule and (2, 2) graphyne nanotube (GNT) has been investigated. The stable configuration due to the insertion of H2O molecule inside (2, 2) GNT is determined on the basis of binding energy. The band gap of the GNT decreases due to the confinement of H2O molecule. The charge analysis reveals that electrons are shifted from the H2O molecule to the GNT. The electronic property of the GNT is highly influenced by the presence of H2O molecule; thus, we may design a GNT based sensor for the detection of water molecule.

Investigations of electronic, chemical and non-linear optical properties of para-chloroacetophenone and meta-chloroacetophenone using density functional theory

Quantum chemical calculations of para-chloroacetophenone (p-CAP) and metacholoroacetophenone (m-CAP) are carried out using 6-311++G(d,p) basis set and two different functionals, HF and B3LYP. The structural parameters are in good agreement with the experimental data. The electric dipole moment, polarizability and first hyperpolarizability values of the two selected compounds have been calculated at the same level of theory and basis set and the results shows that the PCAP can be used as a good non linear optical material. The total electron density and molecular electrostatic potential (MEP) surfaces of the molecules were constructed by using B3LYP/6-311++G(d,p) method to display reactive sites for electrophilic and nucleophilic attack.

Electronic and optical properties of C24, C12X6Y6, and X12Y12 (X = B, Al and Y = N, P)

AbstractUtilizing first-principles calculations, we studied the electronic and optical properties of C24, C12X6Y6, and X12Y12 fullerenes (X = B, Al; Y = N, P). These fullerenes are energetically stable, as demonstrated by their negative cohesive energies. The energy gap of C24 may be tuned by doping, and the B12N12 fullerene was found to have the largest energy gap. All of the fullerenes had finite optical gaps, suggesting that they are optical semiconductors, and they strongly absorb UV radiation, so they could be used in UV light protection devices. They could also be used in solar cells and LEDs due to their low reflectivities. Graphical abstractPossible applications of doped C24 fullerene

The spin filtering effect and negative differential behavior of the graphene-pentalene-graphene molecular junction: a theoretical analysis

AbstractDensity functional theory (DFT) combined with nonequilibrium Green’s function (NEGF) formalism are used to investigate the effects of substitutional doping by nitrogen and sulfur on transport properties of AGNR-pentalene-AGNR nanojunction. A considerable spin filtering capability in a wide bias range is observed for all systems, which may have potential application in spintronics devices. Moreover, all model devices exhibit a negative differential effect with considerable peak-to-valley ratio. Thus, our findings provide a way to produce multifunctional spintronic devices based on nitrogen and sulfur doped pentalene-AGNR nanojunctions. The underlying mechanism for this interesting behavior was exposed by analyzing the transmission spectrum as well as the electrostatic potential distribution. In addition, a system doped with an odd number of dopant shows a rectifying efficiency comparable to other systems. The above findings strongly imply that such a multifunctional molecular device would be a useful candidate for molecular electronics. Graphical abstractThe graphene-pentalene-graphene molecular junction

Electronic properties of aluminium and silicon doped (2, 2) graphyne nanotube

With the help of density functional theory (DFT) approach the electronic properties of Al and Si doped (2, 2) graphyne nanotube (GNT) has been investigated. We have chosen two doping positions. In one situation we have replaced one carbon atom by Al/Si atom in the chain position of the GNT and in other case we have substituted the carbon atom in the hexagonal ring by Al/Si atom. The result of the cohesive energy indicates that pristine graphyne nanotube shows highest stability whereas, Al doped at chain site of the GNT exhibits lowest stability. The density of states above and below the Fermi level for all these system is mainly contributed by carbon atom. Band structure analysis shows that the band gap can be tuned by functionalization of GNT with Al and Si atoms; which makes the possibility of using them in nano-electronic devices.