Microscopic Dynamics of Hard Ellipsoids in their Liquid and Glassy Phase.pdfVIP

1 1 0 0 2 p e S 7 MICROSCOPIC DYNAMICS OF HARD ELLIPSOIDS IN THEIR 1 ] LIQUID AND GLASSY PHASE n n- A. Latz 1, M. Letz 2 , R. Schilling and Th. Theenhaus a s i d. aInstitut f¨ur Physik, Johannes Gutenberg Universit¨at, Mainz D-55099 Mainz, t a Staudinger Weg 7, Germany m- 1 Institut f¨ur Physik, Reichenhainer Strasse 70, TU-Chemnitz, D-09107 Chemnitz, d n Germany o 2 c Schott Glas, Research and Development, Hattenbergstr. 10, D-55014 Mainz, Germany [ 1 To investigate the influence of orientational degrees of freedom onto the dynamics of v 6 molecular systems in its supercooled and glassy regime we have solved numerically the 8 2 mode-coupling equations for hard ellipsoids of revolution. For a wide range of volume 9 fractions φ and aspect ratios x0 we find an orientational peak in the center of mass 0 1 spectra χ′′ (q, ω) and φ′′ (q, ω) about one decade below a high frequency peak. This 0 000 000 / orientational peak is the counterpart of a peak appearing in the quadrupolar spectra t a ′′ ′′ m χ22m (q, ω) and φ22m (q, ω). The latter peak is almost insensitive on φ for x0 close to one, - i.e. for weak steric hindrance, and broadens strongly with increasing x . Deep in the glass d 0 n o we find an additional peak between the orientational and the high frequency peak. We c : have evidence that this intermediate peak is the result of a coupling between modes with v i l = 0 and l = 2, due to the nondiagonality of the static correlators. X r a 1. INTRODUCTION