Isfahan University of Technology, The Physics Society of Iran Iranian Journal of Physics Research 1682-6957 21 4 2022 02 20 Potential energy surface, quartic force fields and vibrational levels of chlorine dioxide anion Potential energy surface, quartic force fields and vibrational levels of chlorine dioxide anion 775 782 1757 10.47176/ijpr.21.4.41238 FA A Shayesteh School of Chemistry, College of Science, University of Tehran, Tehran, Iran 0000-0002-6151-7885 E Falatooni School of Chemistry, College of Science, University of Tehran, Tehran, Iran M Motallebipour School of Chemistry, College of Science, University of Tehran, Tehran, Iran Journal Article 2021 04 23 Potential energy surface was calculated for the ground electronic state of the triatomic ion ClO<sub>2</sub><sup>−</sup> using the coupled-cluster method CCSD(T). Calculations were carried out for 1200 points on the potential energy surface, and the calculated points were fitted to the potential energy expression in terms of the internal coordinates, from which the quadratic, cubic and quartic force fields were determined. Using the second-order rovibrational perturbation theory, harmonic vibrational frequencies, anharmonicity constants and several other spectroscopic parameters were calculated, and accurate fundamental vibrational frequencies were obtained. Also, the energies of 30 lowest vibrational levels were calculated using the anharmonicity constants.<br />  Potential energy surface was calculated for the ground electronic state of the triatomic ion ClO<sub>2</sub><sup>−</sup> using the coupled-cluster method CCSD(T). Calculations were carried out for 1200 points on the potential energy surface, and the calculated points were fitted to the potential energy expression in terms of the internal coordinates, from which the quadratic, cubic and quartic force fields were determined. Using the second-order rovibrational perturbation theory, harmonic vibrational frequencies, anharmonicity constants and several other spectroscopic parameters were calculated, and accurate fundamental vibrational frequencies were obtained. Also, the energies of 30 lowest vibrational levels were calculated using the anharmonicity constants.<br />  potential energy surface coupled cluster method quartic force fields vibrational anharmonicity https://ijpr.iut.ac.ir/article_1757_e11674109d956934497c1195876b1968.pdf