The Stokes-Einstein-Debye relation in ortho-terphenyl liquid

Abstract

The Stokes-Einstein-Debye (SED) relation is proposed to be breakdown in supercooled liquids by many studies. However, the conclusions are usually drawn by testing some variants of the SED relation rather than its original formula. In this work, the rationality of the SED relation and its variants is examined by performing molecular dynamics simulations with the Lewis-Wahnstrom model of ortho-terphenyl (OTP). The results indicate the original SED relation is valid for OTP but the three variants are all breakdown. The inconsistency between SED relation and its variants is analyzed from the heterogeneous dynamics, the adopted assumptions and approximations as well as the interactions among molecules. Therefore, care should be taken when employing the variants to judge the validity of the SED relation in supercooled liquids.