“…However, this model becomes rather complex when the number of atoms is more than 4. Based on the properties of the unitary and special unitary groups, many teams have developed quite different models applied to the vibrational modes of molecular systems and it is worth to mention the works of Van Roosmalen et al [3,4], Lemus and Franck [5] or Hou et al [6]. Interpreting differently the properties of the unitary groups, an algebraic formalism called the U(p + 1) formalism, initially developed by Michelot and Moret-Bailly [7] and Leroy et al [8][9][10][11], has demonstrated its efficiency to reproduce the vibrational level of XY 4 molecular systems, and recently for XY 3 molecular systems such as the stretching modes of AsH 3 [12] and the vibrational modes of the stibine molecule [13].…”