Simulating the vibrational spectra of ionic liquid systems: 1-Ethyl-3-methylimidazolium acetate and its mixtures

Abstract

The vibrational spectra of the ionic liquid 1-ethyl-3-methylimidazolium acetate and its mixtures with water and carbon dioxide are calculated using ab initio molecular dynamics simulations, and the results are compared to experimental data. The new implementation of a normal coordinate analysis in the trajectory analyzer TRAVIS is used to assign the experimentally observed bands to specific molecular vibrations. The applied computational approaches prove to be particularly suitable for the modeling of bulk phase effects on vibrational spectra, which are highly important for the discussion of the microscopic structure in systems with a strong dynamic network of intermolecular interactions, such as ionic liquids.

Voronoi dipole moments for the simulation of bulk phase vibrational spectra

“…Please note that the Wannier spectra are slightly different from the ones shown in ref. 24 as we have changed the default dipole reference point from the center of geometry to the center of mass. The dipole moment of a charged molecule is not uniquely defined, and several possible alternatives in [C 2 C 1 Im][OAc] have been discussed earlier.…”

Computer‐Aided Design of Ionic Liquids as CO2 Absorbents

“…Figure 1s hows the distinction between physical and chemical absorption is possible based on the knowledge of very simple reaction energies and calculated O-C-O angles. However,care has to be taken to obtain the right geometries as demonstrated in Table 2i nw hich we list some critical phenolate ILs.E xperimental capacities clearly point to chemical absorption [14] -physical absorption under the same conditions does not exceed 0.04 mole CO 2 per mole IL;also, measured FTIR spectra revealed additional peaks at approximately 1600 cm À1 ; [14,17] while the 13 CNMR spectrum provided an ew band at d = 161 ppm during the absorption of CO 2 ,t hereby also indicating the formation of carboxylate salts. [14] Gas-phase geometries (O-C-O angles in Table 2) do [b] experimental Gibbs free energies (D r G exp )at2 98.15 Kfor the reaction in Equation (1) for the anions in Ref.…”

En route formation of ion pairs at the ionic liquid–vacuum interface

“…The systems were simulated via molecular dynamics using the DL_POLY package [35] and the LAMMPS package [36,37]. The trajectories were evaluated with our software TraVis [38][39][40][41]. The GRACE program [42] was used to plot the 2D diagrams, and the contour plots were created with gunplot [43].…”