A.F. El-Deeb

Ab initio HF, DFT and experimental (FT-IR) investigation of vibrational spectroscopy of P-N,N-dimethylaminobenzylidenemalononitrile (DBM)

The optimized geometry and vibrational frequencies of P-N,N-dimethylaminobenzylidenemalononitrile (DBM) were obtained by ab initio HF and DFT/B3LYP levels with complete relaxation in the potential energy surface using 6-31++G(d,p) and 6-311++G(d,p) basis sets. The Fourier-transform infrared (FT-IR) spectrum of DBM has been recorded in the region 4000-400 cm(-1). The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR spectrum. The calculated frequencies are in good agreement with the experimental frequencies.

Density functional theory (DFT) investigation of molecular structure and frontier molecular orbitals (FMOs) of P-N,N-dimethylaminobenzylidenemalononitrile (DBM)

P-N,N-dimethylaminobenzylidenemalononitrile (DBM) dye belongs to a class of organic compounds known as molecular rotors. Its optimized geometry and frontier molecular orbitals (FMOs), before and after ultraviolet (UV) irradiation, were obtained by DFT/B3LYP level with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. It is found that the length of C-C bonds of the DBM molecule increases after the UV irradiation, which leads to an increase in its dipole moment making it as a promising material for solar cell applications. Also, its HOMO-LUMO gap decreased from 3.46 to 3.34 eV. From the cyclic voltammetry measurements the value of HOMO-LUMO gap is equal to 3.21 eV. This means that B3LYP/6-311++G(d,p) level of theory is the best one for calculations.