ELECTRONIC STRUCTURE, OPTICAL AND THERMODYNAMIC PROPERTIES OF GERMANIUM-PHENYL NANOCLUSTER IN THE GAS PHASE: A DFT STUDY.

ABSTRACT

The molecular geometry of Germanium-phenyl[Ge₉(C₆H₅)] nanocluster in the gas phase  was studied using ab initio quantum chemical calculation at DFT/B3LYP level of theory employing Lanl2dz basis sets. Themost stable molecular structure of germanium-phenyl nanocluster was predicted using the potential energy surface scan of dihedral angle C₁₀-C₉-Ge₂₀-Ge₃ from 0⁰ to 360⁰ in 10⁰ steps with DFT/MP2 method and CEP-31g basis set as implemented in Gaussian 09 program. This molecular structure was optimized  and their parameters such as bond lengths, bond angles and dihedral angles were computed at this level of theory. The molecular structure, electronic absorption spectra, thermodynamic properties and vibrational frequencies with IR and Raman intensities have been studied. The calculated molecular geometry revealed no imaginary frequencies, is a tricapped trigonal prismatic distorted planar structure and the Ge-Ge bond distance(2.63-2.98 ) and height of 3.126-3.496  similar with observed  experimental values. It is observed that the maximum absorption wavelength( ) corresponds in UV spectrum to an intense maximum peak of 658.8 nm with oscillator strength, in the gas phase. This predicted optical absorption wavelength is within the range of visible spectra of about 400-800 nm. The density of State clearly exhibit the possible energy flow from occupied to the virtual states. The calculated emission spectra  of germanium-phenyl[Ge₉(C₆H₅)] is located in the red visible light region, wavelength( 658.9 nm) and energy(1.882 eV).

Keywords: Germanium, Nanocluster, abinitio, Oscillator Strength, Absorption Wavelength, Geometry Optimization, Potential Energy Surface Scan.