## Efficient Determination of Accurate Force Fields for Porous Materials Using ab Initio Total Energy Calculations

journal contribution

posted on 06.02.2014, 00:00 by Jihan Kim, Li-Chiang Lin, Kyuho Lee, Jeffrey B. Neaton, Berend SmitAccurate characterization of porous
materials is essential for
understanding material properties and evaluating their performance
for potential applications. In general, any methodology that entails
developing an accurate classical force field is computationally expensive
as it requires a large number of quantum mechanical nonempirical calculations.
In order to expedite such calculations without sacrificing too much
accuracy, we have developed a systematic procedure where, starting
from an initial trial force field, accurate adsorption isotherms of
porous materials can be obtained at low computational cost. Specifically,
the procedure involves correcting single-point energy values sampled
from the trial force field in grand canonical Monte Carlo simulations
from few quantum mechanical calculations. We demonstrate that the
methodology yields accurate adsorption data in diverse selection of
guest molecules in porous materials such as CH

_{4}and CO_{2}in zeolites (i.e., MFI, LTA, WEI, RHO, SOD, FAU, RWY, and ABW) and CO_{2}in metal–organic frameworks (i.e., M-MOF-74 with M = Mg, Fe). Furthermore, we use our corrected force fields to predict the adsorption properties of N_{2}in V-MOF-74 and Ti-MOF-74, which are two materials that have yet to be synthesized experimentally. We anticipate that this methodology will be useful in accurately characterizing a given porous material in the absence of a reliable force field as well as for efficiently screening a large number of porous materials.