Molecular dynamics susceptibility

F. Summary The Evolution of the Dynamic Susceptibility above Tg V. Experimental Results of Molecular Glasses (T < Tg)... 

The susceptibility minimum observed in the DS and LS relaxation spectra is a consequence of the interplay of the high-frequency tail of the a-relaxation peak and the contribution from certain fast dynamics dominating at frequencies close to but above the minimum. As was demonstrated by several experimental studies as well as by molecular dynamics simulations (cf. Fig. 13a), in addition to the vibrational contribution a fast relaxation process has to be taken into account for describing correctly the susceptibility minimum [5,9,19,55,64, 133,134,136,147]. This spectral contribution may usually be described by a power law with a positive exponent less than unity. In fact, the search for this fast relaxation process was mostly inspired by MCT, where it naturally appears in the solutions and is interpreted as rattling in the cage type of dynamics. Some authors discussed in addition a constant loss contribution [10,138,222,... 

V. Dubois, P. Umari, and A. Pasquarello (2004) Dielectric susceptibility of dipolar molecular liquids by ab initio molecular dynamics application to liquid HCl. Chem. Phys. Lett. 390, p. 193... 

Nowadays, four-point correlation dynamic susceptibilities or correlation functions x ate discussed to estimate dynamic correlation volumes, x defines the correlation of a molecular motion with respect to both space and time and can be... 

To connect the susceptibility tensor with the molecular dynamics, it is useful to separate the intramolecular from the intermolecular dynamics. This separation is applicable when these two dynamics are decoupled. 

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