Multiorientation Model for Planar Ordering of Trimesic Acid Molecules

Abstract

We present a study of the q-orientational statistical model for the self-assembly of symmetric triangular molecules of trimesic acid in two dimensions. Density functional theory is used to estimate the pair interactions of two such molecules located at the ground state (dimeric H-bond) distance for q 2 different mutual orientations of these molecules. The interaction energies for models with q up to 120 are determined. The Monte Carlo simulation employing these interactions reveals the ordering of the molecules into the honeycomb (HON) phase for the entire range of models (q = 2–120) which is manifested by the peak in temperature dependence of the specific heat C V(T). The increase of q from 2 to 120 causes the ordering temperature T c to decrease and become much closer to the experimental value. Our results imply that in terms of computational efficiency and the magnitude of T c, the q = 12 model is the optimal choice for calculations. The C V(T) dependence has a second peak at a low temperature point T 1 < T c. We find that between T c and T 1, the HON network even at a stoichiometric molecular density still possesses a large portion of filled hexagonal pores and the expulsion of molecules from the pores coincides with the C V peak at T 1. In more refined models (q ≥ 12), the HON phase also displays a slightly distorted bonding geometry from T c down to very low temperature. Finally, our finite size scaling analysis implies that the phase transition in all studied q > 2 models belongs to the three-state Potts universality class.

Molecular Dynamic study of model two-dimensional systems involving Janus dumbbells and spherical particles

“…The conditions of self-organization and morphology of emerging phases formed by anisotropic nanoparticles depend on the presence in the system of other, usually spherical species [25][26][27][28][29][30]. Similar effects to those observed for nanoparticles have also occurred on molecular length scales, namely in the case of formation of supramolecular structures in mixtures involving anisotropic and spherical molecules [31,32]. In both cases, i.e., for nanoparticles, and for molecules organizing into supramolecules, the properties of self-assembled structures depend on the system composition and on the ratio of sizes of the involved components.…”

SuSMoST: Surface Science Modeling and Simulation Toolkit

“…There are lattice models of various degrees of abstraction: Langmuir adsorption model, hard disks, [6,7] dimers, [8][9][10][11] k-mers, [12,13] binary gasses, [14][15][16][17][18] molecules of various symmetry, [19][20][21][22][23] tricarboxylic [24][25][26][27] acids, porphyrins, [28] monoatomic adsobates, [29,30] and so forth. [31,32] In spite of numerous successful applications of lattice models, this kind of simulation is still not a daily tool for surface science researchers.…”

“…Probably this is the reason why contemporary computational studies of surface self-assembly do not refer to available codes, but apparently use inhouse state of art codes. [12,13,20,25]…”

“…Metropolis Monte Carlo is the workhorse and reference method of statistical physics. [52,53] It can be applied to very complex models: with numerous states [25,54] and with long-range interactions. [31,55] It enables one to study any characteristic of adsorption layer because it generates detailed samples as XYZ files.…”

“…Therefore, the lattice with the set of possible site states constitutes the model of the adsorption system. There are lattice models of various degrees of abstraction: Langmuir adsorption model, hard disks, [ 6,7 ] dimers, [ 8–11 ] k ‐mers, [ 12,13 ] binary gasses, [ 14–18 ] molecules of various symmetry, [ 19–23 ] tricarboxylic [ 24–27 ] acids, porphyrins, [ 28 ] monoatomic adsobates, [ 29,30 ] and so forth. [ 31,32 ]…”