10.1021/jp4114283.s001 José da Silva Gomes José da Silva Gomes Ricardo Gargano Ricardo Gargano João B. L. Martins João B. L. Martins Luiz Guilherme M. de Macedo Luiz Guilherme M. de Macedo Relativistic Four-Component Potential Energy Curves for the Lowest 23 Covalent States of Molecular Bromine (Br<sub>2</sub>) American Chemical Society 2014 PEC COSCI covalent states MRCISD spectroscopic constants Lowest 23 Covalent States Br 2 molecule 2014-08-07 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Relativistic_Four_Component_Potential_Energy_Curves_for_the_Lowest_23_Covalent_States_of_Molecular_Bromine_Br_sub_2_sub_/2267005 The covalent excited states and ground state of the Br<sub>2</sub> molecule has been investigated by using four-component relativistic COSCI and MRCISD methods. These methods were performed for all covalent states in the representation Ω<sup>(±)</sup>. Calculated potential energy curves (PECs) were obtained at the four-component COSCI level, and spectroscopic constants (<i>R</i><sub>e</sub>, <i>D</i><sub>e</sub>, <i>D</i><sub>0</sub>, ω<sub>e</sub>, ω<sub>e</sub>x<sub>e</sub>, ω<sub>e</sub><i>y</i><sub>e</sub>, <i>B</i><sub>e</sub>, α<sub>e</sub>, γ<sub>e</sub>, <i>T</i><sub>e</sub>, <i>D</i><sub>v</sub>) for bounded states are reported. The vertical excitations for all covalent states are reported at COSCI, MRCISD, and MRCISD+Q levels. We also present spectroscopic constants for two weakly bounded states (A′:(1)­2<sub>u</sub> and B′:(1)­0<sup>–</sup><sub>u</sub>) not yet reported in the literature, as well as accurate analytical curves for all five relativistic molecular bounded sates [the ground state X:0<sub>g</sub><sup>+</sup> and the excited states A:(1)­1<sub>u</sub>, B:(1)­0<sub>u</sub><sup>+</sup>, C:(2)­1<sub>u</sub>, and B′:(1)­0<sub>u</sub><sup>–</sup>] found in this work.