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The microscopic structure of fluids of simple spheres is well known. However, the constituents of most real-life fluids are non-spherical, leading to a coupling between the rotational and translational degrees of freedom. The structure of simple dense fluids of spheroids - ellipsoids of revolution - was only recently determined by direct experimental techniques [A. P. Cohen, E. Janai, E. Mogilko, A. B. Schofield, and E. Sloutskin, Phys. Rev. Lett. 107, 238301 (2011)]. Using confocal microscopy, it was demonstrated that the structure of these simple fluids cannot be described by hard particle models based on the widely used Percus-Yevick approximation. In this paper, we describe a new protocol for determining the shape of the experimental spheroids, which allows us to expand our previous microscopy measurements of these fluids. To avoid the approximations in the theoretical approach, we have also used molecular dynamics simulations to reproduce the experimental radial distribution functions g(r) and estimate the contribution of charge effects to the interactions. Accounting for these charge effects within the Percus-Yevick framework leads to similar agreement with the experiment. [ABSTRACT FROM AUTHOR]

The field-free orientation induced by a single-cycle terahertz (THz) laser pulse is studied for two 'heavy' molecules, NaI and IBr. Two methods are used and compared in the calculations: One is to solve the exact time-dependent Schrödinger equation (ETDSE) considering the full-rovibrational degrees of freedom, and the other is to invoke the rigid-rotor approximation (RRA). Calculations are performed for the central frequency varying from 0.05 to 1.0 THz and for the peak intensity taken to be 5 × 107, 2 × 108, and 5 × 108 W/cm2, respectively. The degree of field-free orientation, , is strongly dependent on the central frequency and the peak intensity of the single-cycle THz pulse. The maximum degree of field-free orientation is determined to be 0.84 for NaI and 0.63 for IBr in these given ranges of frequency and intensity. The molecular orientation obtained by the RRA calculations is in good agreement with that obtained by the ETDSE in the given parameter region. [ABSTRACT FROM AUTHOR]