Structure and dynamics of mesogens using intermolecular potentials derived from ab initio calculations

Abstract

A method for the calculation of the two-body intermolecular potential which can be applied to large molecules is presented. Each monomer is fragmented in a number of moieties whose interaction energies are used to recover the interaction energy of the whole dimer. For these reasons this strategy has been called fragmentation reconstruction method (FRM). By a judicious choice of the fragmentation scheme it is shown that very accurate interaction energies can be obtained. The sampling of the potential energy surface of a dimer is then used to obtain intermolecular force fields at several levels of complexity, suitable to be employed in bulk phase computer simulations. Applications are presented for benzene and for some mesogenic molecules which constitute the principal interest of the authors. A number of properties ranging from phase stability, thermodynamic quantities, orientational order parameter and collective dynamics properties are computed and discussed

Accuracy of Quantum Mechanically Derived Force-Fields Parameterized from Dispersion-Corrected DFT Data: The Benzene Dimer as a Prototype for Aromatic Interactions

“…In particular, as recently pointed out by Grimme,26 there is a growing attention to novel parameterization strategies, based solely on QM data, capable of yielding very accurate FFs. 4,17,19,[23][24][25][26][27][28][29][30][31][32][33][34][35][36] Despite the rather large number of different strategies, there are only few protocols, up to our knowledge, capable to parameterize specific FFs (both intramolecular and intermolecular) to be used in condensed phase simulations. Indeed, most of the proposed procedures 17,21,23,24 focus on the parameterization of the intramolecular part of the FF, deriving the parameters for the bonded interactions (e.g.…”

Force‐field modeling through quantum mechanical calculations: Molecular dynamics simulations of a nematogenic molecule in its condensed phases

“…In the latter case, the intermolecular energy of 5CB was computed for many dimer arrangements by employing the fragmentation reconstruction method (FRM),21, 22 proposed by our group to calculate the interaction energy of large molecules. The resulting database was then used to yield, through fitting procedures, an intermolecular model potential suitable for MD simulations 23.…”

Reparameterization of 12-6 Lennard-Jones potentials based on quantum mechanism results for novel tetrahedral N4 (Td) explosives

“…To parameterize intermolecular force fields from ab initio calculations, least-squares fitting of a large number of single point energies of gas-phase dimer with various configurations is needed [32,[37][38][39][40]. Therefore, the sampling of the dimer configurations to well respond intermolecular interactions in the bulk phase is crucial.…”