Simulation study of discotic molecules in the vicinity of the isotropic–liquid crystal transition

Martínez–Haya, Bruno; Cuetos, Alejandro

doi:10.1080/08927020902833111

Cited by 14 publications

(12 citation statements)

References 24 publications

(43 reference statements)

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“…8,14,15 an isotropic fluid at the lowest densities for all aspect ratios L/D, a (discotic) nematic phase at low densities and aspect ratio L/D 0.1, and phases in which the OHSC form aligned columns at high densities. However, using the pressure annealing method, we found two different crystals, X tilted and X aligned , which were found to be stable (using free energy calculations) in, respectively, the lower and 46 the transition from D ho to D hd , where the correlation length of the particles within a column becomes smaller than a certain threshold value (e.g., a few particle dimensions) is not sharp at all; the spatial correlations within a column will always have a finite correlation length.…”

Section: Phase Diagrammentioning

confidence: 99%

“…8,13,14,[18][19][20][21][22][23] Therefore, we will only briefly describe the shape of our platelets. The OHSC consists of a flat cylindrical core with diameter σ and height L, and a toroidal rim, with tube diameter L (see Fig.…”

Section: Modelmentioning

confidence: 99%

“…Defining the potential in this way preserves the shape of the particles. [14][15][16] In Refs. 8,14, and 15, the phase diagram of oblate hard spherocylinders (OHSC) was tentatively explored using direct simulations.…”

Section: Introductionmentioning

confidence: 99%

“…[14][15][16] In Refs. 8,14, and 15, the phase diagram of oblate hard spherocylinders (OHSC) was tentatively explored using direct simulations. Three columnar phases were found for 0.1 ≤ L/D ≤ 0.5, where L is the thickness of the platelet and D its diameter.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the phase diagram, the maximum packing fractions of the various crystals are shown, which is of use to predict the phase behavior at infinite pressures. Well-packed structures can also serve as candidate crystal structures for other disklike systems (for instance repulsiveattractive disks [14][15][16] ).…”

Section: Introductionmentioning

confidence: 99%

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Phase behavior of hard colloidal platelets using free energy calculations

Maréchal

Cuetos

Martínez–Haya

et al. 2011

The Journal of Chemical Physics

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We investigate the phase behavior of a model for colloidal hard platelets and rigid discotic molecules: oblate hard spherocylinders (OHSC). We perform free energy calculations using Monte Carlo simulations to map out the phase diagram as a function of the aspect ratio L/D of the particles. The phase diagram displays a stable isotropic phase, a nematic liquid crystal phase for L/D ≤ 0.12, a columnar phase for L/D 0.3, a tilted crystal phase for L 0.45, and an aligned crystal phase for L/D 0.45. We compare the results to the known phase diagram of hard cut spheres. Thin cut spheres are almost cylinder-shaped, while the interactions between real discotic mesogens and colloidal platelets are more consistent with the toroidal rims of the OHSC. Since the shapes of the OHSC and the cut spheres are otherwise similar, the phase diagrams of the two types of particles are quite akin. However, the tilted crystal phase for OHSC, which is of a crystal type that is frequently found in experiments on disklike molecules, has not been found for hard cut spheres. Furthermore, although we have found a cubatic phase, it was shown to be definitely unstable, whereas the stability of the cubatic phase of cut spheres is still disputed. Finally, we also show that the phase boundaries differ significantly from those for cut spheres. These are remarkable consequences of a subtle change in particle shape, which show that for a detailed comparison with the phase behavior of experimental particles, the OHSC should be used as a model particle.

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Section: Phase Diagrammentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phase behavior of hard colloidal platelets using free energy calculations

Maréchal

Cuetos

Martínez–Haya

et al. 2011

The Journal of Chemical Physics

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Toward Transferable Coarse‐Grained Potentials for Poly‐Aromatic Hydrocarbons: A Force Matching Approach

Tripathy

Agarwal

Kumar

2018

Macro Theory & Simulations

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Poly‐aromatic hydrocarbons (PAHs) have been the subject of numerous experimental investigations for their multitude of existence, from particulate soot to the vast cosmos. Given the structural peculiarity of PAHs, where aromatic moieties serve as the basic building blocks, a generalized coarse‐grained (CG) description befits and holds immense potential to investigate large‐scale PAH systems and their derivatives via CG simulation. Toward this, a minimal CG mapping scheme is proposed where a set of PAHs are modeled as planar molecules made up of oblate ellipsoids, which interact via uniaxial Gay–Berne (GB) potential. A force‐based systematic coarse‐graining approach is followed to extract the CG force field parameters. The resulting GB parameters are found to be either comparable or show definite trends as a function of molecular size. CG simulation is shown to retain the qualitative structural features of the underlying atomistic systems with multi‐fold decrease in computational cost. Accelerated equilibration of atomistic systems is shown to be achievable by MC simulations of CG systems followed by back‐mapping, where the atomistic structure is exactly reproduced.

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