Ab Initio Molecular Dynamics Simulations of the Infrared Spectra of H3O2(-) and D3O2(.).

We present the infrared spectra of H3O2(-) and D3O2(-) calculated using MP2 direct molecular dynamics approach at temperatures of 100 and 300 K. The spectral peaks were assigned using the normal-mode analysis, instantaneous normal-mode analysis, isotopic substitution, polarized infrared absorptions, and analysis of the position-position correlation function. Our results predict the bridging hydrogen stretch between 600 and 900 cm(-1) and bridging hydrogen bend vibrations between 1250 and 1650 cm(-1). We also examine two DFT methods (B3PW91 and B3LYP) and report on the differences between them and the MP2 spectra.