Molecular hydrodynamic theory of non‐Markovian collective orientational relaxation in dense dipolar liquids

Vijayadamodar , GV and Bagchi, B (1991) Molecular hydrodynamic theory of non‐Markovian collective orientational relaxation in dense dipolar liquids. In: Journal of Chemical Physics, The, 95 (7). pp. 5289-5299.

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Abstract

A microscopic study of the non‐Markovian (or memory) effects on the collective orientational relaxation in a dense dipolar liquid is carried out by using an extended hydrodynamic approach which provides a reliable description of the dynamical processes occuring at the molecular length scales. Detailed calculations of the wave‐vector dependent orientational correlation functions are presented. The memory effects are found to play an important role; the non‐Markovian results differ considerably from that of the Markovian theory. In particular, a slow long‐time decay of the longitudinal orientational correlation function is observed for dense liquids which becomes weaker in the presence of a sizeable translational contribution to the collective orientational relaxation. This slow decay can be attributed to the intermolecular correlations at the molecular length scales. The longitudinal component of the orientational correlation function becomes oscillatory in the underdamped limit of momenta relaxations and the frequency dependence of the friction reduce the frictional resistance on the collective excitations (commonly known as dipolarons) to make them long lived. The theory predicts that these dipolarons can, therefore, be important in chemical relaxation processes, in contradiction to the claims of some earlier theoretical studies.

Item Type:	Journal Article
Publication:	Journal of Chemical Physics, The
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Keywords:	Mode-Coupling Theory;Velocity Correlation-Function; Auto-Correlation Function;Dielectric-Relaxation;Polar Liquids;Dynamics;Frequency;Behavior;Time;Solvation.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	24 Nov 2010 09:35
Last Modified:	24 Nov 2010 09:35
URI:	http://eprints.iisc.ac.in/id/eprint/33994

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