Lyapunov instability of rigid diatomic molecules in three dimensions - art. no. 041106

We study the Lyapunov instability of a three-dimensional fluid composed of rigid diatomic molecules by molecular dynamics simulation. We use center-of -mass coordinates and angular variables for the configurational space varia bles. The spectra of Lyapunov exponents are obtained for 32 rigid diatomic molecules interacting through the Weeks-Chandler-Andersen potential for var ious bond lengths and densities. We show the general trends and characteris tic features of the spectra of the Lyapunov exponents, and discuss the diff erent contributions between translational and rotational degrees of freedom depending on the density and the bond length from the calculation of the p rojection of a certain subspace of the tangent space vectors.