Ph.D. Thesis

Density Functional Investigation on Structure and Physicochemical Properties of some Clusters, Compounds and Materials

(January 2014 - February 2018)

Supervisor: Asst. Prof. Dr. Debesh R. Roy

Department of Applied Physics, S.V. National Institute of Technology-Surat, INDIA.

The research work in the present thesis employs DFT for the investigation of some 0D-atomic clusters and organic/inorganic molecules, 2D-ultrathin nanosheets, 3D-bulk compounds and single/parallel molecular electronic circuit. DFT based electronic descriptors, e.g. HOMO-LUMO gap, ionization potential, electron affinity, electronegativity, hardness, polarizability, hyperpolarizability, electrophilicity etc. are utilized for evaluation of the electronic structure and stability of the atomic clusters and molecules. The aromaticity is also derived through the nucleas-independent chemical shift (NICS) for the cage based systems. The optical absorption spectra and vibrational frequency spectra are calculated which can aid researchers for experimental studies of the sub-nanostructured endohedral fullerenes, PMMA and metal doped porphyrins, chromium clusters and their anions and oxides, and inorganic hexagonal thallium pnictide clusters. The electronic structure and properties are understood from the predicted band structure and density of states (DOS) for the inorganic thallium nitride nanosheets and bulk metal chalcogenide compounds. Appropriate thermoelectrical and optical parameters are also calculated and analyzed for searching their relevant applications. Finally, the thesis ends with a detail study on single/parallel molecular electronic circuit.

Master Thesis

DFT Investigation on: Electronic, Thermodynamic and Optical Properties of Telluride Compounds

(August 2012- July 2013)

Supervisors: Asst. Prof. Dr. Debesh R. Roy and Asst. Prof. Dr. D.V. Shah

Department of Applied Physics, S.V. National Institute of Technology-Surat, INDIA.

A detail and comparative study on electronic, thermodynamic and non-linear optical (NLO) properties of seven telluride compounds, viz., XTe (X=Bi, Cd, Pb, Zn), X₂Te₃ (X=Bi, Sb) and X₂Y_xTe_3-x (X=Bi, Y=Se, x=0 to 0.3) are performed under the density functional formalism. Various electronic, thermodynamic and NLO parameters are utilized for the prediction of best telluride candidates towards different application directions. A very popular hybrid exchange-correlation functional B3LYP, as proposed by A. D. Becke, is employed for these purposes under the density functional theory (DFT). It is evident from the present study that CdTe is the best candidate for possible conductivity whereas Sb₂Te₃ is found to be the most favorable for NLO materials.

Internship Experience

Growth and Characterization of Nickel, Nickel Iron and Lithium Fluoride Thin Films

(May-August 2011)

Supervisors: Prof. Christian Bernhard and Dr. Leander Schultz

Solid State Physics Group of Department of Physics at the University of Fribourg, SWITZERLAND.

Experimental Fabrication of nanometer scaled thin films of nickel, nickel iron and lithium fluoride quartz base was carried out by thermal evaporator. Thin Films were characterized for Structural and Magnetic properties. Structural properties like film thickness, density and surface roughness were obtained from the data analysis of measurements done by XRR technique. The magnetic measurements were done using PPMS-VSM technique. A detailed analysis of the same helped extracting properties like magnetic saturation and hysteresis natures of the materials selected.

Introduction to Magnetic Materials and X-Ray Diffraction

(May-August 2010)

Supervisor: Prof. K. G. Suresh

Department of Physics at Indian Institute of Technology-Bombay, INDIA.

Preparation of powdered magnetic crystalline samples and examination of the samples utilizing X-Ray Diffraction technique was done. Simulations of the data obtained from the XRD measurements, involving Brillouin Function and Einstein and Debye model were applied for extraction of the paramagnetic magnetization and specific heat.