In this work we use Density-Functional Tight-Binding (DFTB) to investigate dynamical processes dependent on the flexibility in metal–organic frameworks (MOFs). We show that one can perform DFTB simulations on systems having unit cells of several hundreds atoms at a modest computational cost. This approach is validated by calculating the barriers to diffusion for small molecules (hydrogen, carbon dioxide, and methane) crossing the windows connecting the pores of ZIF-7 and ZIF-8, two prototypical materials that have been the subject of many experimental and theoretical investigations. Additionally, we calculate the vibrational densities of states for MOF-5 and ZIF-8. These calculations are compared with simulations using the bonded and non-bonded part of the Universal Force Field (UFF). The results show that UFF’s description of the bonded interactions has a quality comparable to DFTB’s, at an even smaller computational cost.

Modeling flexibility in Metal-Organic Frameworks: comparison between Density-Functional Tight-Binding and Universal Force Field approaches for bonded interactions

Garberoglio, Giovanni;Taioli, Simone
2012

Abstract

In this work we use Density-Functional Tight-Binding (DFTB) to investigate dynamical processes dependent on the flexibility in metal–organic frameworks (MOFs). We show that one can perform DFTB simulations on systems having unit cells of several hundreds atoms at a modest computational cost. This approach is validated by calculating the barriers to diffusion for small molecules (hydrogen, carbon dioxide, and methane) crossing the windows connecting the pores of ZIF-7 and ZIF-8, two prototypical materials that have been the subject of many experimental and theoretical investigations. Additionally, we calculate the vibrational densities of states for MOF-5 and ZIF-8. These calculations are compared with simulations using the bonded and non-bonded part of the Universal Force Field (UFF). The results show that UFF’s description of the bonded interactions has a quality comparable to DFTB’s, at an even smaller computational cost.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11582/84201
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
social impact