An automated approach for the parameterization of accurate intermolecular force-fields: pyridine as a case study.

An automated protocol is proposed and validated, which integrates accurate quantum mechanical calculations with classical numerical simulations. Intermolecular force fields, (FF) suitable for molecular dynamics (MD) and Monte Carlo simulations, are parameterized through a novel iterative approach, fully based on quantum mechanical data, which has been automated and coded into the PICKY software, here presented. The whole procedure is tested and validated for pyridine, whose bulk phase, described through MD simulations performed with the specifically parameterized FF, is characterized by computing several of its thermodynamic, structural, and transport properties, comparing them with their experimental counterparts.

Geometry Optimization of Large and Flexible van der Waals Dimers: A Fragmentation-Reconstruction Approach.

A novel approach for exploring the energy minima of the potential energy surface of large and flexible van der Waals dimers is proposed and tested. The total dimer energy is divided into intra- and intermolecular contributions, which can be computed at different levels of theory. The intermolecular energy, which is the time-consuming part of the calculation, is computed by means of the fragmentation reconstruction method (FRM), making possible the calculation of the interaction energy of large molecules.

Solvent-induced stereochemical behavior of a bile acid-based biphenyl phosphite: a computational study.

The origin of the stereochemical behavior experimentally found in a bile acid-derived biphenyl phosphite is studied by means of quantum mechanical methods. The molecular mechanisms driving the screw sense of the dihedral angle between the two phenyl rings of the biphenyl phosphite unit are investigated with density functional theory calculations. Energy, geometry, and circular dichroism spectra have been computed and compared between the two resulting diastereoisomers.

Chemical Detail Force Fields for Mesogenic Molecules.

Intra- and intermolecular potential energy surfaces of the 4,4'-di-n-heptyl azoxybenzene molecule have been sampled by ab initio calculations and represented through a force field suitable for classical bulk simulations. The parametrization of the molecular internal flexibility has been performed by a fitting procedure based on single molecule Hessian, gradients and torsional energies, computed using density functional theory. The intermolecular part of the force field has been derived as a pure pair potential, by fitting the dimer potential energy surface sampled by the Fragmentation Reconstruction Method.