Given the psychoactive effects of dimethyltryptamine (DMT), classified as a Schedule I drug, developing diagnostic methods is essential. In this computational study, we investigate the adsorption and sensing behavior of DMT on pristine C20 fullerene and its beryllium (Be), magnesium (Mg), and calcium (Ca) doped derivatives using density functional theory (DFT), time-dependent DFT (TD-DFT), and quantum theory of atoms in molecules (QTAIM) to provide suitable candidates that reduce trial-and-error in subsequent experimental work. Three computational methods (B97D/lanl2dz, B97D/6-311 + G(d), and ωB97XD/lanl2dz) were employed to ensure the accuracy of qualitative results. Our results reveal that pristine C20 and BeC19 exhibit strong adsorption characterized by donor-acceptor interactions, electrostatic attraction, polarization/charge transfer, and dispersion forces. Electronic structure analysis indicates that BeC19 exhibits the largest reduction in Egap upon DMT adsorption, accompanied by pronounced charge transfer and substantial modulation of conductivity. UV-Vis spectra show that C20 and BeC19 exhibit a significant redshift from the UV to the visible region after DMT absorption, making them candidates for further experimental evaluation as colorimetric sensors. NCI, ELF, LOL, and QTAIM analyses confirm that interactions are predominantly non-covalent, with Be doping introducing localized attractive regions that enhance sensitivity. In contrast, MgC19 and CaC19 show minimal electronic perturbation and weak adsorption dominated by van der Waals forces. Statistical validation using MAD, RMSD, and Pearson correlation coefficients (R > 0.93) confirms good qualitative agreement across all computational methods. These theoretical findings suggest pure C20 as a potential adsorbent and BeC19 as a dual-purpose material for adsorption and electrochemical/colorimetric detection of DMT for further experimental work in the future, and provide a theoretical basis for the development of future experimental sensors.
