Mining the Cambridge Database for theoretical chemistry. Mi-LJC: a new set of Lennard-Jones–Coulomb atom–atom potentials for the computer simulation of organic condensed matter

CrystEngComm ◽  
2020 ◽  
Vol 22 (43) ◽  
pp. 7350-7360 ◽  
Author(s):  
Angelo Gavezzotti ◽  
Leonardo Lo Presti ◽  
Silvia Rizzato
Keyword(s):  
Computer Simulation ◽  
Force Field ◽  
Condensed Matter ◽  
Molecular Crystals ◽  
Theoretical Chemistry ◽  
Lennard Jones ◽  
Force Field Parametrization

A novel, universal Lennard-Jones–Coulomb (LJC) atom–atom force field parametrization reproduces the experimental sublimation enthalpies of 377 molecular crystals drawn from the CSD.

Development of the trappe force field for ammonia

2010 ◽  
Vol 75 (5) ◽  
pp. 577-591 ◽  
Author(s):  
Ling Zhang ◽  
J. Ilja Siepmann
Keyword(s):  
Dielectric Constant ◽  
Nitrogen Atom ◽  
Force Field ◽  
Electrostatic Interactions ◽  
Hydrogen Atoms ◽  
Site Model ◽  
Lennard Jones ◽  
Hydrogen Position ◽  
Partial Charges ◽  
Vapor Liquid

The transferable potentials for phase equilibria (TraPPE) force field is extended through the development of a non-polarizable five-site ammonia model. In this model, the electrostatic interactions are represented by three positive partial charges placed at the hydrogen position and a compensating partial charge placed on an M site that is located on the C3 molecular axis and displaced from the nitrogen atom toward the hydrogen atoms. The repulsive and dispersive interactions are represented by placing a single Lennard–Jones site at the position of the nitrogen atom. Starting from the five-site model by Impey and Klein (Chem. Phys. Lett. 1984, 104, 579), this work optimizes the Lennard–Jones parameters and the magnitude of the partial charges for three values of the M site displacement. This parameterization is done by fitting to the vapor–liquid coexistence curve of neat ammonia. The accuracy of the three resulting models (differing in the displacement of the M site) is assessed through computation of the binary vapor–liquid equilibria with methane, the structure and the dielectric constant of liquid ammonia. The five-site model with an intermediate displacement of 0.08 Å for the M site yields a much better value for the dielectric constant, whereas differences in the other properties are quite small.

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