Prediction of Growth-Induced Polarity in Centrosymmetric Molecular Crystals Using Force Field Methods

Abstract

A three-step procedure is proposed to investigate growth-induced polarity arising in centrosymmetric crystals of dipolar molecules. It is based on (i) calculation of molecular interaction energies by force field methods, (ii) determination of the morphology, and (iii) use of the energies in a Markov-type growth mechanism on faces (hkl). Applied to trans-4-chloro-4‘-nitrostilbene (CNS), the procedure showed that CNS crystals, although globally centric, are composed of sectors exhibiting different polar properties. The sectors related to the +b and −b directions show opposite polarity and are mainly responsible for observed second-harmonic generation and pyroelectric effects. Influence of the calculation method on the results was investigated by comparing different force fields or charges.

Growth-induced polarity formation in solid solutions of organic molecules: Markov mean-field model and Monte Carlo simulations

“…16 In order to reduce the number of independent interaction energies, the following assumptions are made concerning longitudinal interaction energies involving G molecules: 16 In order to reduce the number of independent interaction energies, the following assumptions are made concerning longitudinal interaction energies involving G molecules:…”

“…16 However, crystal structures generally require a more detailed description in terms of lattice symmetries, interaction energies, and growth process.…”

Polarity formation by a higher order interaction Markov-like chain

“…far reaching dipolar intermolecular interactions, a cut-off at ξ = 3 is set here, since an extension to a higher order would not have a significant chemical impact. Also force field calculations show that the main energetic effect results from the first and the second coordination environment in molecular crystals [9].…”

A partition function‐based weighting scheme in force field parameter development using ab initio calculation results in global configurational space

“…[1][2][3][4][5] The total potential energy of a molecular system is a sum of the contributions from various intramolecular terms and intermolecular terms. [7,15] Generally, NBI are considered to be critical properties in molecular systems such as molecular association, [4,5,16] ligand-receptor binding, [17][18][19] property analysis of materials [20] and liquids, [21,22] and process research such as studying interface and adsorption. The intermolecular or nonbonded interactions (NBI) contain the van der Waals (vdW) term represented by the Lennard-Jones (LJ) type or less commonly the exponential type potential, and the electrostatic term represented by a Coulombic potential.…”