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

Abstract

Interaction energy of the 4-n-pentyloxy-4'-cyanobiphenyl (5OCB) dimer is computed at MP2 level, for many geometrical arrangements using the Fragmentation Reconstruction Method (FRM). DFT calculations are performed for a number of geometries of the monomer. The resulting database is used to parameterize an atomistic intra- and inter-molecular force-field suitable for classical bulk simulations. Several structural and dynamical properties in 5OCB isotropic and liquid crystalline phases are computed from molecular dynamics simulation mainly in the NPT ensemble. Lengthy runs (more than 70 ns) and large sample sizes (up to 806 molecules) were used to determine the nematic to isotropic transition temperature up to a precision of few K. Good agreement was found in most of the investigated properties, thus validating the accuracy of the proposed model potential, only derived by quantum mechanical calculations.

An insight into de Vries behaviour of smectic liquid crystals from atomistic molecular dynamics simulations

“…As a result, many studies have focused on the parameterisation and verification of force fields, with the application of both experimental and theoretical approaches. [75][76][77] Although many force fields aim to be able to predict experimental properties for a range of compounds, force fields that have been parameterised for accurate prediction of a specific family of molecules often lack the ability to perform well when applied to a different series of compounds. As a result, while general force fields are known to give less accurate predictions of absolute experimental values, they may be used to model experimental trends in a broader range of compounds and provide a means to assess phase structure under simulated conditions.…”

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.…”

Validating an optimized GAFF force field for liquid crystals: TNI predictions for bent-core mesogens and the first atomistic predictions of a dark conglomerate phase

“…7 Two of the most sensitive liquid crystal macroscopic properties to reproduce, and crucial for technological applications, are the T NI transition temperature (clearing temperature) and the thermal stability range of the nematic phase. 8 Unfortunately, the use of standard force fields for the study of liquid crystal systems often produces poor results. For example, simulated results for 5CB and 8CB employing AMBER, OPLS and the General AMBER force field (GAFF) have reported transition temperatures (T NI and T SN ) approximately 33 -120 K above experimental values.…”