Scaled Quantum Mechanical Force Fields for the Peroxynitrates. I. Acetyl Peroxynitrate and Trifluoroacetyl Peroxynitrate

Abstract The vibrational properties of acetyl peroxynitrate CH 3 C(O)OONO 2 (PAN) and trifluoroacetyl peroxynitrate CF 3 C(O)OONO 2 (FPAN) were studied by means of density functional theory (DFT) methods. The previously available experimental data and assignments for these compounds were compared with the theoretical results and revised, and a complete description of the 23 normal modes of vibration observed for each molecule is proposed. The assignments were used in the definition of scaled quantum mechanics (SQM) force fields for such molecules. In addition, the internal force constants were obtained as a parameter typical of each chemical bond.