The infrared spectrum of the O⋯H⋯O fragment of H5O2+: Ab initio classical molecular dynamics and quantum 4D model calculations

Abstract

Articles you may be interested inAnharmonic force field and vibrational dynamics of CH2F2 up to 5000 cm−1 studied by Fourier transform infrared spectroscopy and state-of-the-art ab initio calculations Quantum and classical studies of vibrational motion of CH 5 + on a global potential energy surface obtained from a novel ab initio direct dynamics approachThe gas phase IR spectrum of the O¯H¯O fragment of H 5 O 2 ϩ and its deuterated analogue are calculated using ab initio classical molecular dynamics based on a MP2 potential energy surface. The assignment of the bands is made in terms of the quantum four-dimensional model calculations of anharmonic frequencies and intensities. Comparing low and high kinetic temperature simulations the importance of anharmonicities of the potential energy surface for understanding the vibrational band structure is highlighted. It is shown that any reasonable simulation of IR spectra of systems with very strong hydrogen bonds has to account for the dipole moment function beyond the linear approximation.

IR Spectrum of the H5O2+ Cation in the Context of Proton Disolvates L−H+−L

“…At 1 K the proton is on average displaced from its equilibrium position by only about 0.01 Å. 35 With increasing temperature, the proton displacements along the flat bottom of the potential well increase significantly, reaching up to 0.2 Å at 360 K. 35 As a result, the proton coordinates are subject to a large fluctuation that results in substantial mechanical and electrooptic anharmonicity. This is expected to significantly complicate the calculated IR spectrum.…”

“…This is expected to significantly complicate the calculated IR spectrum. The most recent calculations (4D) of Vener et al 35 take anharmonicity into account and show coupling between all four frequencies of the shared proton. At this level of theory, the fundamental bending frequencies γ(OHO) and δ(OHO) for the free H 5 O 2 + ion are ca.…”

“…This is in accord with the recent calculations of Vener. 35 The remaining question is why the δ(H 2 O) band, observed in the gas-phase spectrum of H 5 O 2 + near 1700 cm -1 , is not observed (or is very weak) in the condensed phase. The answer may lie in a peculiarity of the IR spectra of symmetrical proton disolvates.…”

Effect of hydrogen bonding on the infrared absorption intensity of OH stretch vibrations

“…Unfortunately, an experimental measurement of the absolute intensity seems unavailable. Theoretical studies also give the relative intensities of this mode to be 3-10, 46 8, 47 and 20-40 48 times the intensity of the OH stretches of the end groups. For (CH 3 OH) 2 H + , the OH stretch at 1010 cm −1 (also 0 − ← 0 + in our notation) was computed to have an intensity of 2567 km/mol 44 .…”

Gas‐Phase Infrared Spectrum of the Protonated Water Dimer: Molecular Dynamics Simulation and Accuracy of the Potential Energy Surface

“…+ in the 500-2000 cm À1 region (in which the modes of the bridging proton are expected) by Asmis et al [1] has raised questions [2,3] about the assignment [4] of the observed bands and stimulated more experimental work. [3,5,6] Most recently, infrared predissociation (IRPD) spectroscopy has been applied to the complex of H 5 O 2 + with Ar, [5,6] and the spectrum obtained shows some differences to that obtained by IRMPD.…”