The molecular structure of 4-methoxybenzaldehyde (4MBA) was optimized by the DFT/B3LYP method with 6-311++G(d,p) basis set. The complete vibrational assignment and analysis of the fundamental modes of the compound are carried out using the experimental FTIR and FT-Raman spectra. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been studied using NBO and AIM topological analysis. Molecular electrostatic potential, Mulliken and natural atomic charge distributions are calculated. The frontier orbital energy gap and related properties of the molecule illustrates the high reactivity of the title compound. The non-linear optical properties of the compound have been discussed by measuring the dipole moment, the polarizability and hyperpolarizability tensors. Finally, the thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase.
