Fortunatus, Jacob2024-06-172024-06-172022-04-12https://repository.udsm.ac.tz/handle/123456789/6088Geometrical parameters and vibrational spectra of the dimer Ba2X4 molecules were calculated; diferent isomeric structures were revealed. For the Ba2F4, Ba2Cl4, and Ba2Br4, three isomers of C3v, C2v, and C2h symmetries were confrmed to exist while for Ba2I4 only two isomers, C3v and C2h, were confrmed. For all halides, the bipyramidal C3v isomers possessed the lowest energy. The structural parameters and vibrational frequencies were employed in calculation of thermodynamic func tions and enthalpies of dissociation reactions of the species. The enthalpies of formation ∆fH(0) of the C3v isomers were obtained (in kJ mol−1):−1874 ± 2 (Ba2F4);−1236 ± 7 (Ba2Cl4);−1023 ± 8 (Ba2Br4);−787 ± 11 (Ba2I4). The relative abundance of the isomeric forms was evaluated for a broad temperature range, between 200 and 2000 K. It was shown that the concentrations of different isomers appeared to be comparable in saturated vapors at temperatures close to experimental conditions.enDFTMP2MP4vibrational spectraenthalpy of formationJournal Articlehttps://doi.org/10.1007/s11224-022-01936-w