Van Speybroeck, Veronique

Vandichel, Matthias

Vanduyfhuys, Louis

Verstraelen, Toon

Waroquier, Michel

English

Ghent University Academic Bibliography

Ab initio parametrized force field for the flexible metal organic framework MIL-53(Al)L. Vanduyfhuys, T. Verstraelen, M. Vandichel, M. Waroquier, V. Van SpeybroeckCenter for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde, BelgiumA force field is proposed for the flexible metal-organic framework MIL-53(Al), which is calibrated  using  density  functional  theory  calculations  on  non-periodic  clusters[1]. The force field has three main contributions: an electrostatic term based on atomic charges derived with a modified Hirshfeld-I method, a van der Waals (vdW) term with  parameters  taken  from  the  MM3  model  [2]  and  a  valence  force  field  whose parameters were estimated with a new methodology that  uses the gradients and Hessian matrix elements retrieved from non-periodic cluster calculations. Figure 1: Energy profiles of the breathing mode after uniformly rescaling (a) the  vdW-interaction strength (b) the vdW radii by a factor indicated above each curve.  The experimental lines of lp and np are taken from Ref. 3The new force field, predicts geometries and cell parameters that compare well with the experimental  values both  for  the large and narrow pore phases.  The energy profile along the breathing mode of the empty material (Fig. 1) reveals the existence of two minima, which confirms the intrinsic bistable behaviour of the MIL-53. Even without the stimulus of external guest molecules the material may transform from the large pore (lp) to the narrow pore (np) phase [3]. The relative stability of the two phases critically depends on the vdW parameters and MM3 dispersion interaction has the tendency to overstabilize the np phase.[1]  Vanduyfhuys et al., submitted to J. Chem.Theory Comput.[2]  Allinger et al. J. Am. Chem. Soc. 1989, 111, 8551[3]  Liu et al. J. Am. Chem. Soc. 2008, 120, 11813

Ab initio parametrised force field for the flexible metal-organic framework MIL-53(Al)

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Ab initio parametrised force field for the flexible metal-organic framework MIL-53(Al)

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Ghent University Academic Bibliography