Hydrogen bonding in the protic ionic liquid triethylammonium nitrate explored by density functional tight binding simulations

Zentel, Tobias; Kühn, Oliver

doi:10.1063/1.4972006

Cited by 15 publications

(20 citation statements)

References 58 publications

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“…At the IPT transition state, agreement remains good, 1.196 Å using DFTB versus 1.203 and 1.205 Å using M06‐2X/aug‐cc‐pVTZ and MP2/aug‐cc‐pVTZ, respectively. The close agreement here, particularly with reference to the transition state structure, is attributed to the third order correction to the DFTB method which is known to improve the description of hydrogen bonding …”

Section: Resultssupporting

confidence: 60%

Density functional tight binding‐based free energy simulations in the DFTB+ program

2018

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The timescale problem-in which high barriers on the free energy surface trap molecular dynamics simulations in local energy wells-is a key limitation of current reactive MD simulations based on the density functional tight binding (DFTB) potential. Here, we report a new interface between the DFTB+ software package and the PLUMED library for performing DFTB-based free energy calculations. We demonstrate the performance of this interface for 3 archetypal rare-event chemical reactions, (i) intramolecular proton transfer in malonaldehyde, (ii) bowl inversion in corannulene, and (iii) oxygen diffusion on graphene. Using third-order DFTB in conjunction with metadynamics (with/without multiple walkers) and welltempered metadynamics, we report here free energies of activation (ΔG ‡ ) of 13.1 AE 0.4, 48.2 AE 1.7, and 52.0 AE 6.2 kJ mol −1 , respectively, for these processes. In each case, our DFTB free energy barriers and local minima compare favorably with previous literature results, demonstrating the utility of the DFTB+ -PLUMED interface.

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Section: Resultssupporting

confidence: 60%

Density functional tight binding‐based free energy simulations in the DFTB+ program

2018

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“…Here, starting from the HB distances, r NH and r OH , bond orders are defined as p i = exp(−(r i − r eq i )/b i ) with i = {NH, OH} and r eq i being the gas phase equilibrium bond distances. Under the constraint that the sum of the two bond orders must equal one, the two coordinates depend on each other and the HB geometry change along a proton transfer reaction [19] (all values inÅ).…”

Section: H-bond Geometriesmentioning

confidence: 99%

“…This analysis was previously performed for triethylammonium nitrate (TEAN) using a similar setup [19]. The resulting parameters of the valence bond order model are also given in table 1.…”

Section: H-bond Geometriesmentioning

confidence: 99%

Hydrogen bonding in protic ionic liquids: structural correlations, vibrational spectroscopy, and rotational dynamics of liquid ethylammonium nitrate

Zentel

Overbeck

Michalik

et al. 2018

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. The properties of the hydrogen bonds in ethylammonium nitrate are analyzed by using molecular dynamics simulations and infrared as well as nuclear magnetic resonance experiments. Ethylammonium nitrate features a flexible three-dimensional network of hydrogen bonds with moderate strengths, which makes it distinct from related triethylammonium-based ionic liquids. First, the network's flexibility is manifested in a not very pronounced correlation of the hydrogen bond geometries, which is caused by rapid interchanges of bonding partners. The large flexibility of the network leads to a substantial broadening of the mid-IR absorption band, with the contributions due to N-H stretching motions ranging from 2800 to 3250 cm −1 . Finally, the different dynamics are also seen in the rotational correlation of the N-H bond vector, where a correlation time as short as 16.1 ps is observed.

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“…Concerning IR spectroscopy and in particular signatures of HB dynamics the use of force fields is problematic, since the parametrization of the latter is often targeted to thermodynamic quantities, see, e.g., Ref. [23]. Here, DFT-based ab initio molecular dynamics (AIMD) provides the proper frame for more accurate simulations [24,13,25].…”

Section: Introductionmentioning

confidence: 99%

Properties of hydrogen bonds in the protic ionic liquid ethylammonium nitrate

Zentel

Kühn

2017

Theor Chem Acc

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Comparative molecular dynamics simulations of a hexamer cluster of the protic ionic liquid ethylammonium nitrate are performed using density functional theory (DFT) and density functional-based tight binding (DFTB) methods. The focus is on assessing the performance of the DFTB approach to describe the dynamics and infrared spectroscopic signatures of hydrogen bonding between the ions. Average geometries and geometric correlations are found to be rather similar. The same holds true for the far-infrared spectral region. Differences are more pronounced for the NH-and CHstretching band, where DFTB predicts a broader intensity distribution. DFTB completely fails to describe the fingerprint range shaped by nitrate anion vibrations. Finally, charge fluctuations within the H-bonds are characterized yielding moderate dependencies on geometry. On the basis of these results, DFTB is recommend for the simulation of H-bond properties of this type of ionic liquids.

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Hydrogen bonding in the protic ionic liquid triethylammonium nitrate explored by density functional tight binding simulations

Cited by 15 publications

References 58 publications

Density functional tight binding‐based free energy simulations in the DFTB+ program

Density functional tight binding‐based free energy simulations in the DFTB+ program

Hydrogen bonding in protic ionic liquids: structural correlations, vibrational spectroscopy, and rotational dynamics of liquid ethylammonium nitrate

Properties of hydrogen bonds in the protic ionic liquid ethylammonium nitrate

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