Computational studies of vibrational spectra and molecular properties of 6-methyluracil using HF, DFT and MP2 methods |
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Authors: | Tabish Rasheed and Shabbir Ahmad |
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Institution: | (1) Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands;(2) Instituci? Catalana de Recerca i Estudis Avan?ats (ICREA), 08010 Barcelona, Spain and Institut de Qu?mica Computacional, Universitat de Girona, Campus Montilivi, 17071 Girona, Spain;(3) Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA |
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Abstract: | Theoretical investigations of atomic charges, conformers, frontier molecular orbitals, molecular geometries, thermodynamic
properties, hyperpolarizabilities and harmonic vibrational frequencies of 6-methyluracil (6MU) have been carried out using
ab initio Hartree-Fock (HF), density functional theory (DFT) and second order M?ller-Plesset (MP2) methods. All calculations were performed
using the GAMESS-US program package with the basis sets 6-31G(d,p) and 6-311G(d,p). FT-IR and Raman spectra of 6MU were recorded
in the regions 50–4000 cm−1 and 60–4000 cm−1 respectively. Optimized geometries were obtained using the global optimization procedure. The calculated structural parameters
for two conformers of 6MU have been compared with experimentally observed values. The energy barrier (ΔE=ELUMO-EHOMO) between
the HOMO and LUMO is predicted on the basis of theoretical calculations. The simulated TD-DFT spectrum has been compared with
experimental electronic spectrum for 6MU. The calculated potential energy distribution (PED) values have been utilized to
perform vibrational assignment of the infrared and Raman spectra. |
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