First Principles Study on the Stability and Electronic Structures of 7,8-Dichloro-4-Oxo-4H-Chromene-3-Carbaldehyde

The molecular structures and electronic properties of 7,8-Dichloro-4-Oxo-4H-Chromene-3-Carbaldehyde, C10H4Cl2O3 have been studied using Density Functional Theory (DFT) method. The calculation of geometry optimization was conducted to find the local energy minimum of C10H4Cl2O3 molecular system. The equilibrium geometries were used to determine the HOMO-LUMO gaps, Mulliken atomic charges, and other electronic structures of C10H4Cl2O3. The significant findings from DFT/B3LYP functional within the basis sets of 6-31G**, 6-31++G**, 6-311G**, and 6-311++G** show that the optimized geometries of C10H4Cl2O3 are in good agreement with that of measurement data. To further investigate this, using a variety of basis sets (3-21G, 6-31G, 6-31++G, 6-31G**, 6-31++G**, 6-311G, 6-311++G, 6-311G**, and 6-311++G**), it is found that the calculated total energy values of C10H4Cl2O3 are close to each other. Similarly, the computed HOMO-LUMO energy gaps obtained are also close to each other. Using the scheme of Mulliken Population Analysis (MPA), the trend of findings are the same for both cases of B3LYP/6-31G and B3LYP/6-31G** level of calculations. For the method of B3LYP/6-31G, it is clearly found that C4 and C6 have the highest positively charge, with the corresponding values about +0.284 and +0.238, respectively. On the other hand, the charge values of +0.157 and +0.206 are found on Cl1 and Cl2 atoms. The atoms of O1, O2, and O3 have the negatively charges, with the values of about 0.398, -0.512, and -0.424, respectively. Similarly, in the case of DFT/B3LYP/6-31G** level of theory, the computed charge values of C2 and C4 are about +0.311 and +0.393, respectively. Furthermore, the Cl1 and Cl2 atoms have the positively charge values of about +0.043 and +0.070, whereas for the O1, O2, and O3 atoms, the charges values obtained are about -0.421, -0.467, and -0.498, respectively.