We use nonequilibrium molecular dynamics simulations to investigate the structural properties of an oriented melt of $n$-eicosane under steady-state planar elongational flow. The flow-induced structure was evaluated using the structure factor $s\left(k\right)$ taken as the Fourier transform of the total pair correlation function $g\left(r\right)$. We found that the equilibrium liquid structure factor is in excellent agreement with the one determined via x-ray diffraction. Moreover, a new x-ray diffraction experiment has been performed on a crystalline $n$-eicosane sample. The resulting intramolecular contribution to the structure factor was found to be in very good agreement with the simulated one at a high elongation rate, indicating the existence of a possible crystalline precursor structure.

• Received 11 October 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.037802