IJSRST18459 | Received : 01 March 2018 | Accepted : 10 March 2018 | March-April-2018 [ (4) 5 : 81-89 ] © 2018 IJSRST | Volume 4 | Issue 5 | Print ISSN: 2395-6011 | Online ISSN: 2395-602X Themed Section: Science and Technology 81 Synthesis, Growth, Physicochemical Properties and DFT Calculations on Nonlinear Optical Single Crystal of L-Histidine Dinitrate for Frequency Conversion Applications K. Deepa 1 , S. Senthil 2 , J. Madhavan *1 1 Department of Physics, Loyola College, Chennai, Tamil Nadu, India 2 Department of Physics, Government Arts College for Men, Nandanam, Chennai, Tamil Nadu, India ABSTRACT Single crystals of L-Histidine Dinitrate (LHDN) have been successfully grown by slow solvent evaporation technique at room temperature. Powder X-Ray diffraction patterns has been recorded and indexed for the analysis of crystalline nature and the lattice parameters of the grown crystals. L-Histidine Dinitrate crystallizes in orthorhombic space group P212121 and it exhibit second order non-linear optical (NLO) susceptibility due to the intermolecular charge transfer. The functional groups are identified by Fourier transform infrared spectral analysis and compared with theoretical spectrum. The optical transmission range of the LHDN crystal has measured by UV–Vis–NIR studies. It is observed that the minimum absorption in the entire visible and ultra violet range of 240–1500 nm. From absorption spectra the optical band gap is found to be 4.89 eV. Theoretically Simulated XRD pattern of LHDN single crystal has been carried out. Vibration frequencies are calculated using B3LYP/6-31+G (d,p) and B3LYP/6-311++ G(d, p) . Vibration mode assignments were also compared with the experimental results. The optimized geometrical parameters, fundamental vibrational frequencies, IR intensity, Raman activity, atomic small charges, dipole moment, reduced mass, force constant and other thermodynamic parameters were calculated. The second harmonic generation (SHG) efficiency has been carried out and it reveals the NLO property of the crystals. The HOMO and LUMO analysis were used to determine the charge transfer within the molecule and quantum chemical parameters related to the LHDN compound. Keywords : Powder XRD, optical absorption, Density Functional Theory, HOMO-LUMO analysis, FTIR, SHG efficiency I. INTRODUCTION Intensive research effort has been concerted on the investigation of the nonlinear optical processes in π- conjugated organic molecules and materials in the recent past decades [1, 2]. The rapid and sustained growth of the field is mainly due to the technological promise of these materials. The utmost importance in the design strategy for efficient non-linear optical (NLO) materials in terms of the molecular design and the supramolecular aggregation is basically aimed to accomplish their potential applications in various photonic technologies. This overwhelming approach crafts a sole field of intriguing explorations in chemical synthesis, molecular and material characterization, theoretical modeling, and NLO studies and photonics technology [3]. The molecular NLO active crystals have been intensively studied to establish the observed structure function correlation through the computational modeling of molecules as the origin of the nonlinear optical response in such systems are governed by the electronic polarizability of the electrons at the molecular level [4] as well as the geometrical arrangement of the NLO-