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Int. J. Electroactive Mater. 5 (2017) 19-30

Thermodynamical Properties and Infrared Spectra of 4-n-propoxy-4´- cyanobiphenyl: Hartree-Fock and Density Functional Theory Methodsdy

Dipendra Sharma1*, Sugriva Nath Tiwari2

1Physics, DDU Gorakhpur University, Gorakhpur, Gorakhpur, Uttar Pradesh, India
2Physics, DDU Gorakhpur University, Gorakhpur, U. P., India

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Abstract : The members of the 4-n-alkoxy-4´-cyanobiphenyl (nOCB) homologus series are well known for their electro-optic properties. 4-n-propoxy-4´-cyanobiphenyl (3OCB) is a homologue of this liquid crystal series. The 3OCB is a nematic liquid crystal which transforms from crystal to isotropic phase at 74.5⁰C and isotropic to nematic phase at 64.0⁰C. Molecular geometry of 3OCB has been optimized by Hartree-Fock-HF/6-31G(d,p) and density functional theory-B3LYP/6-31G(d,p) methods using GAMESS program. Conformational analysis and molecular charge distribution calculation have been carried out. The MEP, HOMO and LUMO surfaces have been scanned. Molecular and thermodynamical properties have been examined. Further, vibrational assignment of the molecule has been performed. Results obtained by HF and DFT techniques have been compared and analysed. Further, efforts have been made to elucidate thermodynamic properties, infrared spectra, vibration frequencies and photochemical activity of the 3OCB liquid crystal system.

Keywords : Liquid crystal,PES,MEP,HOMO,LUMO,FTIR spectrum