Gradientless parallel geometry optimization of Bi$_5^{3+}$ cluster and its luminescent properties

The results of quantum-chemistry calculations of ground and excited states of the bismuth polycation Bi$_5^{3+}$ are discussed. The polycation geometries that correspond to a minimum of energy of excited states are found. The SO-CI (spin-orbital configurational interaction) are used in calculations. In order to optimize the energies of excited states of the Bi$_5^{3+}$ cluster, a gradientless minimization algorithm is proposed. A program that implements this algorithm for parallel data processing on multiple cores is developed. A significant influence of the Jahn-Teller effect on the luminescent properties of the bismuth polycation is shown.