Deuterium nuclear magnetic resonance study of the orientational order in the nematic phase of 4-n-pentyloxy-4′-cyanobiphenyl. Tests of the Emsley–Luckhurst–Stockley theory and of the Haller extrapolation

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

“…Conversely, the behavior of the high temperature run at 350 K clearly shows a nematic to isotropic transition upon heating, which takes place in the first 5 ns of simulation. Thereafter the order parameter relaxes to an equilibrium value of 0.07, much more similar to that reported in experimental data39, 63–66 with respect to the P 2 computed for the smaller 192 molecules sample.…”

“…The presence of orientational order is also well reproduced, despite P 2 at 330 K is slightly lower than the value determined, at the same temperature, from dielectric relaxation data 66. Despite the measured values are rather scattered, depending on the employed experimental technique,39, 63–66 the P 2 range for 5OCB in its nematic phase can be delimited between 0.3 and 0.7. The computed value 0.4 is well within this range and well compares with the values of 0.4 and 0.32 reported66 at 337 and just below the transition temperature at 340 K, respectively.…”

Nematic order parameter as determined from dielectric relaxation data and other methods

“…3-7 (left hand sides) present the obtained results together with other data available in the literature. The functional form of S(T ) is often approximated by the formula proposed by Haller 19 SðTÞ ¼ S 0 ðT NI À TÞ g ð6Þ with two adjustable parameters S 0 and g. Heeks and Luckhurst 20 have found that eqn. ( 6) works rather well for S-values determined for 5OCB from the NMR measurements (compare Fig.…”

“…( 6 Fig. 4 (a) The order parameter for 5OCB derived from different experiments: NMR ( 2 H), 20 NMR ( 13 C) 23 optical birefringence (Dn), 16 refractive indices (n), 24 and dielectric relaxation data according to formulae ( 3) and ( 4). The lines are fits of eqn.…”

Twist-bend nematic phase of the liquid crystal dimer CB7CB: orientational order and conical angle determined by129Xe and2H NMR spectroscopy

“…Values of the parameters, extracted from the fits of Equation (10) to the experimental 2 H quadrupolar splittings in the nematic and twist-bend nematic phases of CB7CB-d 4. Nematic phase N T NI = 388 K representation of the temperature dependence of the order parameter for the para-axis. [35] As a result, the assumptions made in the analysis of the quadrupolar splittings seem more likely to be valid for the monomer probe than for its dimer host. The deuterium NMR experiments and the results for the quadrupolar splittings for 8CB-d 2 dissolved in the two nematic phases of CB7CB are described by Beguin et al [4] The plot of their data for this solution, given in Figure 19 of their paper, [4] certainly mimics the results found for CB7CB-d 4 and shown in Figure 8, quite closely.…”