Publication Details
Abstract
This study aims to conduct a comprehensive theoretical analysis of the structural, electronic and vibrational properties of the organic compound tetrathiafulvalene (TTF), based on Density Functional Theory (DFT) and employing the Dmol³ quantum computational program. Three different exchange–correlation functionals—LDA-PWC, GGA-PBE, and the hybrid B3LYP—were utilized to compare their performance in describing the molecular characteristics of TTF. Geometry optimization revealed noticeable variations in bond lengths and angles depending on the chosen functional, with B3LYP demonstrating the closest agreement with reference experimental data. The analysis of the frontier molecular orbitals (HOMO and LUMO) showed significant differences in the energy gap, where B3LYP again proved to be more accurate in predicting electronic stability and chemical reactivity. Global chemical reactivity descriptors—such as ionization potential, electron affinity, chemical hardness and softness, electronegativity, and electrophilicity index—were also calculated, and the results using B3LYP showed strong consistency with previously reported theoretical values. Furthermore, the vibrational spectrum of TTF was computationally examined and categorized into three regions: a low-frequency region (0–1000 cm⁻¹) corresponding to sulfur atom bending and C–S bond modes; a mid-frequency region (1000–1600 cm⁻¹) involving C=C stretching and C–H bending vibrations; and a high-frequency region (1600–3200 cm⁻¹) associated with high-energy C–H stretching. Slight differences in peak positions and intensities were observed among the functionals, attributed to variations in the treatment of electron exchange and correlation. Overall, the study underscores the importance of functional selection in theoretical modeling and offers valuable insights into the behavior of the TTF molecule, reinforcing its potential for applications in organic electronics and advanced materials.